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Add a new unreg_all() callback that can be used to remove all
command-specific triggers from an event and arrange to have it called
whenever a trigger file is opened with O_TRUNC set.
Commands that don't want truncate semantics, or existing commands that
don't implement this function simply do nothing and their triggers
remain intact.
Link: http://lkml.kernel.org/r/2b7d62854d01f28c19185e1bbb8f826f385edfba.1449767187.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Add a new needs_rec flag for triggers that require unconditional
access to trace records in order to function.
Normally a trigger requires access to the contents of a trace record
only if it has a filter associated with it (since filters need the
contents of a record in order to make a filtering decision). Some
types of triggers, such as 'hist' triggers, require access to trace
record contents independent of the presence of filters, so add a new
flag for those triggers.
Link: http://lkml.kernel.org/r/7be8fa38f9b90fdb6c47ca0f98d20a07b9fd512b.1449767187.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Add a simple per-trigger 'paused' flag, allowing individual triggers
to pause. We could leave it to individual triggers that need this
functionality to do it themselves, but we also want to allow other
events to control pausing, so add it to the trigger data.
Link: http://lkml.kernel.org/r/fed37e4879684d7dcc57fe00ce0cbf170032b06d.1449767187.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Add a utility function to grab the syscall name from the syscall
metadata, given a syscall id.
Link: http://lkml.kernel.org/r/be26a8dfe3f15e16a837799f1c1e2b4d62742843.1449767187.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Some triggers may need access to the trace event, so pass it in. Also
fix up the existing trigger funcs and their callers.
Link: http://lkml.kernel.org/r/543e31e9fc445ef61077421ab219033401c39846.1449767187.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Make various event trigger utility functions available outside of
trace_events_trigger.c so that new triggers can be defined outside of
that file.
Link: http://lkml.kernel.org/r/4a40c1695dd43cac6cd475d72e13ffe30ba84bff.1449767187.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Make is_string_field() and is_function_field() accessible outside of
trace_event_filters.c for other users of ftrace_event_fields.
Link: http://lkml.kernel.org/r/2d3f00d3311702e556e82eed7754bae6f017939f.1449767187.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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When I was updating the ftrace_stress test of ltp. I encountered
a strange phenomemon, excute following steps:
echo nop > /sys/kernel/debug/tracing/current_tracer
echo 0 > /sys/kernel/debug/tracing/options/funcgraph-cpu
bash: echo: write error: Invalid argument
check dmesg:
[ 1024.903855] nop_test_refuse flag set to 0: we refuse.Now cat trace_options to see the result
The reason is that the trace option test will randomly setup trace
option under tracing/options no matter what the current_tracer is.
but the set_tracer_option is always using the set_flag callback
from the current_tracer. This patch adds a pointer to tracer_flags
and make it point to the tracer it belongs to. When the option is
setup, the set_flag of the right tracer will be used no matter
what the the current_tracer is.
And the old dummy_tracer_flags is used for all the tracers which
doesn't have a tracer_flags, having issue to use it to save the
pointer of a tracer. So remove it and use dynamic dummy tracer_flags
for tracers needing a dummy tracer_flags, as a result, there are no
tracers sharing tracer_flags, so remove the check code.
And save the current tracer to trace_option_dentry seems not good as
it may waste mem space when mount the debug/trace fs more than one time.
Link: http://lkml.kernel.org/r/1457444222-8654-1-git-send-email-chuhu@redhat.com
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
[ Fixed up function tracer options to work with the change ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Commit e91467ecd1ef ("bug in futex unqueue_me") introduced a barrier() in
unqueue_me() to prevent the compiler from rereading the lock pointer which
might change after a check for NULL.
Replace the barrier() with a READ_ONCE() for the following reasons:
1) READ_ONCE() is a weaker form of barrier() that affects only the specific
load operation, while barrier() is a general compiler level memory barrier.
READ_ONCE() was not available at the time when the barrier was added.
2) Aside of that READ_ONCE() is descriptive and self explainatory while a
barrier without comment is not clear to the casual reader.
No functional change.
[ tglx: Massaged changelog ]
Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Darren Hart <dvhart@linux.intel.com>
Cc: dave@stgolabs.net
Cc: peterz@infradead.org
Cc: linux@rasmusvillemoes.dk
Cc: akpm@linux-foundation.org
Cc: fengguang.wu@intel.com
Cc: bigeasy@linutronix.de
Link: http://lkml.kernel.org/r/1457314344-5685-1-git-send-email-nasa4836@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/nohz
Pull nohz enhancements from Frederic Weisbecker:
"Currently in nohz full configs, the tick dependency is checked
asynchronously by nohz code from interrupt and context switch for each
concerned subsystem with a set of function provided by these. Such
functions are made of many conditions and details that can be heavyweight
as they are called on fastpath: sched_can_stop_tick(),
posix_cpu_timer_can_stop_tick(), perf_event_can_stop_tick()...
Thomas suggested a few months ago to make that tick dependency check
synchronous. Instead of checking subsystems details from each interrupt
to guess if the tick can be stopped, every subsystem that may have a tick
dependency should set itself a flag specifying the state of that
dependency. This way we can verify if we can stop the tick with a single
lightweight mask check on fast path.
This conversion from a pull to a push model to implement tick dependency
is the core feature of this patchset that is split into:
* Nohz wide kick simplification
* Improve nohz tracing
* Introduce tick dependency mask
* Migrate scheduler, posix timers, perf events and sched clock tick
dependencies to the tick dependency mask."
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The callers of steal_account_process_tick() expect it to return
whether a jiffy should be considered stolen or not.
Currently the return value of steal_account_process_tick() is in
units of cputime, which vary between either jiffies or nsecs
depending on CONFIG_VIRT_CPU_ACCOUNTING_GEN.
If cputime has nsecs granularity and there is a tiny amount of
stolen time (a few nsecs, say) then we will consider the entire
tick stolen and will not account the tick on user/system/idle,
causing /proc/stats to show invalid data.
The fix is to change steal_account_process_tick() to accumulate
the stolen time and only account it once it's worth a jiffy.
(Thanks to Frederic Weisbecker for suggestions to fix a bug in my
first version of the patch.)
Signed-off-by: Chris Friesen <chris.friesen@windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/56DBBDB8.40305@mail.usask.ca
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The dl_new field of struct sched_dl_entity is currently used to
identify new deadline tasks, so that their deadline and runtime
can be properly initialised.
However, these tasks can be easily identified by checking if
their deadline is smaller than the current time when they switch
to SCHED_DEADLINE. So, dl_new can be removed by introducing this
check in switched_to_dl(); this allows to simplify the
SCHED_DEADLINE code.
Signed-off-by: Luca Abeni <luca.abeni@unitn.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1457350024-7825-2-git-send-email-luca.abeni@unitn.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The error path in perf_event_open() is such that asking for a sampling
event on a PMU that doesn't generate interrupts will end up in dropping
the perf_sched_count even though it hasn't been incremented for this
event yet.
Given a sufficient amount of these calls, we'll end up disabling
scheduler's jump label even though we'd still have active events in the
system, thereby facilitating the arrival of the infernal regions upon us.
I'm fixing this by moving account_event() inside perf_event_alloc().
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/1456917854-29427-1-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Newer GCC versions trigger the following warning:
kernel/time/timekeeping.c: In function ‘get_device_system_crosststamp’:
kernel/time/timekeeping.c:987:5: warning: ‘clock_was_set_seq’ may be used uninitialized in this function [-Wmaybe-uninitialized]
if (discontinuity) {
^
kernel/time/timekeeping.c:1045:15: note: ‘clock_was_set_seq’ was declared here
unsigned int clock_was_set_seq;
^
GCC clearly is unable to recognize that the 'do_interp' boolean tracks
the initialization status of 'clock_was_set_seq'.
The GCC version used was:
gcc version 5.3.1 20151207 (Red Hat 5.3.1-2) (GCC)
Work it around by initializing clock_was_set_seq to 0. Compilers that
are able to recognize the code flow will eliminate the unnecessary
initialization.
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The check for the AP range in cpuhp_is_ap_state() is redundant after commit
8df3e07e7f21 "cpu/hotplug: Let upcoming cpu bring itself fully up" because all
states above CPUHP_BRINGUP_CPU are invoked on the hotplugged cpu. Remove it.
Reported-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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On CPU hotplug the steal time accounting can keep a stale rq->prev_steal_time
value over CPU down and up. So after the CPU comes up again the delta
calculation in steal_account_process_tick() wreckages itself due to the
unsigned math:
u64 steal = paravirt_steal_clock(smp_processor_id());
steal -= this_rq()->prev_steal_time;
So if steal is smaller than rq->prev_steal_time we end up with an insane large
value which then gets added to rq->prev_steal_time, resulting in a permanent
wreckage of the accounting. As a consequence the per CPU stats in /proc/stat
become stale.
Nice trick to tell the world how idle the system is (100%) while the CPU is
100% busy running tasks. Though we prefer realistic numbers.
None of the accounting values which use a previous value to account for
fractions is reset at CPU hotplug time. update_rq_clock_task() has a sanity
check for prev_irq_time and prev_steal_time_rq, but that sanity check solely
deals with clock warps and limits the /proc/stat visible wreckage. The
prev_time values are still wrong.
Solution is simple: Reset rq->prev_*_time when the CPU is plugged in again.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: <stable@vger.kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: commit 095c0aa83e52 "sched: adjust scheduler cpu power for stolen time"
Fixes: commit aa483808516c "sched: Remove irq time from available CPU power"
Fixes: commit e6e6685accfa "KVM guest: Steal time accounting"
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1603041539490.3686@nanos
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fix from Steven Rostedt:
"A feature was added in 4.3 that allowed users to filter trace points
on a tasks "comm" field. But this prevented filtering on a comm field
that is within a trace event (like sched_migrate_task).
When trying to filter on when a program migrated, this change
prevented the filtering of the sched_migrate_task.
To fix this, the event fields are examined first, and then the extra
fields like "comm" and "cpu" are examined. Also, instead of testing
to assign the comm filter function based on the field's name, the
generic comm field is given a new filter type (FILTER_COMM). When
this field is used to filter the type is checked. The same is done
for the cpu filter field.
Two new special filter types are added: "COMM" and "CPU". This allows
users to still filter the tasks comm for events that have "comm" as
one of their fields, in cases that users would like to filter
sched_migrate_task on the comm of the task that called the event, and
not the comm of the task that is being migrated"
* tag 'trace-fixes-v4.5-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Do not have 'comm' filter override event 'comm' field
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Commit 9f61668073a8d "tracing: Allow triggers to filter for CPU ids and
process names" added a 'comm' filter that will filter events based on the
current tasks struct 'comm'. But this now hides the ability to filter events
that have a 'comm' field too. For example, sched_migrate_task trace event.
That has a 'comm' field of the task to be migrated.
echo 'comm == "bash"' > events/sched_migrate_task/filter
will now filter all sched_migrate_task events for tasks named "bash" that
migrates other tasks (in interrupt context), instead of seeing when "bash"
itself gets migrated.
This fix requires a couple of changes.
1) Change the look up order for filter predicates to look at the events
fields before looking at the generic filters.
2) Instead of basing the filter function off of the "comm" name, have the
generic "comm" filter have its own filter_type (FILTER_COMM). Test
against the type instead of the name to assign the filter function.
3) Add a new "COMM" filter that works just like "comm" but will filter based
on the current task, even if the trace event contains a "comm" field.
Do the same for "cpu" field, adding a FILTER_CPU and a filter "CPU".
Cc: stable@vger.kernel.org # v4.3+
Fixes: 9f61668073a8d "tracing: Allow triggers to filter for CPU ids and process names"
Reported-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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https://git.linaro.org/people/john.stultz/linux into timers/core
Pull the cross-timestamp infrastructure from John Stultz.
Allows precise correlation of device timestamps with system time. Primary use
cases being PTP and audio.
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git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs into next
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Make the identifier public key and digest algorithm fields text instead of
enum.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
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The existing sequences of operations ensure that the offlining csses
are drained before cgroup_update_dfl_csses(), so even though
cgroup_update_dfl_csses() uses css_for_each_descendant_pre() to walk
the target cgroups, it doesn't end up operating on dead cgroups.
Also, the function explicitly excludes the subtree root from
operation.
This is fragile and inconsistent with the rest of css update
operations. This patch updates cgroup_update_dfl_csses() to use
cgroup_for_each_live_descendant_pre() instead and include the subtree
root.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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During prep, cgroup_setup_root() allocates cgrp_cset_links matching
the number of existing css_sets to later link the new root. This is
fine for now as the only operation which can happen inbetween is
rebind_subsystems() and rebinding of empty subsystems doesn't create
new css_sets.
However, while not yet allowed, with the recent reimplementation,
rebind_subsystems() can rebind subsystems with descendant csses and
thus can create new css_sets. This patch makes cgroup_setup_root()
allocate 2x of the existing css_sets so that later use of live
subsystem rebinding doesn't blow up.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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cgroup_calc_subtree_ss_mask() currently takes @cgrp and
@subtree_control. @cgrp is used for two purposes - to decide whether
it's for default hierarchy and the mask of available subsystems. The
former doesn't matter as the results are the same regardless. The
latter can be specified directly through a subsystem mask.
This patch makes cgroup_calc_subtree_ss_mask() perform the same
calculations for both default and legacy hierarchies and take
@this_ss_mask for available subsystems. @cgrp is no longer used and
dropped. This is to allow using the function in contexts where
available controllers can't be decided from the cgroup.
v2: cgroup_refres_subtree_ss_mask() is removed by a previous patch.
Updated accordingly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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rebind_subsystem() open codes quite a bit of css and interface file
manipulations. It tries to be fail-safe but doesn't quite achieve it.
It can be greatly simplified by using the new css management helpers.
This patch reimplements rebind_subsytsems() using
cgroup_apply_control() and friends.
* The half-baked rollback on file creation failure is dropped. It is
an extremely cold path, failure isn't critical, and, aside from
kernel bugs, the only reason it can fail is memory allocation
failure which pretty much doesn't happen for small allocations.
* As cgroup_apply_control_disable() is now used to clean up root
cgroup on rebind, make sure that it doesn't end up killing root
csses.
* All callers of rebind_subsystems() are updated to use
cgroup_lock_and_drain_offline() as the apply_control functions
require drained subtree.
* This leaves cgroup_refresh_subtree_ss_mask() without any user.
Removed.
* css_populate_dir() and css_clear_dir() no longer needs
@cgrp_override parameter. Dropped.
* While at it, add WARN_ON() to rebind_subsystem() calls which are
expected to always succeed just in case.
While the rules visible to userland aren't changed, this
reimplementation not only simplifies rebind_subsystems() but also
allows it to disable and enable csses recursively. This can be used
to implement more flexible rebinding.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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cgroup_create() manually updates control masks and creates child csses
which cgroup_mkdir() then manually populates. Both can be simplified
by using cgroup_apply_enable_control() and friends. The only catch is
that it calls css_populate_dir() with NULL cgroup->kn during
cgroup_create(). This is worked around by making the function noop on
NULL kn.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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cgroup_drain_offline() is used to wait for csses being offlined to
uninstall itself from cgroup->subsys[] array so that new csses can be
installed. The function's only user, cgroup_subtree_control_write(),
calls it after performing some checks and restarts the whole process
via restart_syscall() if draining has to release cgroup_mutex to wait.
This can be simplified by draining before other synchronized
operations so that there's nothing to restart. This patch converts
cgroup_drain_offline() to cgroup_lock_and_drain_offline() which
performs both locking and draining and updates cgroup_kn_lock_live()
use it instead of cgroup_mutex() if requested. This combined locking
and draining operations are easier to use and less error-prone.
While at it, add WARNs in control_apply functions which triggers if
the subtree isn't properly drained.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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cgroup_subtree_control_write()
Factor out cgroup_{apply|finalize}_control() so that control mask
update can be done in several simple steps. This patch doesn't
introduce behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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While controllers are being enabled and disabled in
cgroup_subtree_control_write(), the original subsystem masks are
stashed in local variables so that they can be restored if the
operation fails in the middle.
This patch adds dedicated fields to struct cgroup to be used instead
of the local variables and implements functions to stash the current
values, propagate the changes and restore them recursively. Combined
with the previous changes, this makes subsystem management operations
fully recursive and modularlized. This will be used to expand cgroup
core functionalities.
While at it, remove now unused @css_enable and @css_disable from
cgroup_subtree_control_write().
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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cgroup_apply_control_{disable|enable}() recursive
The three factored out css management operations -
cgroup_drain_offline() and cgroup_apply_control_{disable|enable}() -
only depend on the current state of the target cgroups and idempotent
and thus can be easily made to operate on the subtree instead of the
immediate children.
This patch introduces the iterators which walk live subtree and
converts the three functions to operate on the subtree including self
instead of the children. While this leads to spurious walking and be
slightly more expensive, it will allow them to be used for wider scope
of operations.
Note that cgroup_drain_offline() now tests for whether a css is dying
before trying to drain it. This is to avoid trying to drain live
csses as there can be mix of live and dying csses in a subtree unlike
children of the same parent.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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cgroup_subtree_control_write()
Factor out css enabling and showing into cgroup_apply_control_enable().
* Nest subsystem walk inside child walk. The child walk will later be
converted to subtree walk which is a bit more expensive.
* Instead of operating on the differential masks @css_enable, simply
enable or show csses according to the current cgroup_control() and
cgroup_ss_mask(). This leads to the same result and is simpler and
more robust.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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cgroup_subtree_control_write()
Factor out css disabling and hiding into cgroup_apply_control_disable().
* Nest subsystem walk inside child walk. The child walk will later be
converted to subtree walk which is a bit more expensive.
* Instead of operating on the differential masks @css_enable and
@css_disable, simply disable or hide csses according to the current
cgroup_control() and cgroup_ss_mask(). This leads to the same
result and is simpler and more robust.
* This allows error handling path to share the same code.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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Factor out async css offline draining into cgroup_drain_offline().
* Nest subsystem walk inside child walk. The child walk will later be
converted to subtree walk which is a bit more expensive.
* Relocate the draining above subsystem mask preparation, which
doesn't create any behavior differences but helps further
refactoring.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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When a controller is enabled and visible on a non-root cgroup is
determined by subtree_control and subtree_ss_mask of the parent
cgroup. For a root cgroup, by the type of the hierarchy and which
controllers are attached to it. Deciding the above on each usage is
fragile and unnecessarily complicates the users.
This patch introduces cgroup_control() and cgroup_ss_mask() which
calculate and return the [visibly] enabled subsyste mask for the
specified cgroup and conver the existing usages.
* cgroup_e_css() is restructured for simplicity.
* cgroup_calc_subtree_ss_mask() and cgroup_subtree_control_write() no
longer need to distinguish root and non-root cases.
* With cgroup_control(), cgroup_controllers_show() can now handle both
root and non-root cases. cgroup_root_controllers_show() is removed.
v2: cgroup_control() updated to yield the correct result on v1
hierarchies too. cgroup_subtree_control_write() converted.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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We're in the process of refactoring cgroup and css management paths to
separate them out to eventually allow cgroups which aren't visible
through cgroup fs. This patch factors out cgroup_create() out of
cgroup_mkdir(). cgroup_create() contains all internal object creation
and initialization. cgroup_mkdir() uses cgroup_create() to create the
internal cgroup and adds interface directory and file creation.
This patch doesn't cause any behavior differences.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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Currently, operations to initialize internal objects and create
interface directory and files are intermixed in cgroup_mkdir(). We're
in the process of refactoring cgroup and css management paths to
separate them out to eventually allow cgroups which aren't visible
through cgroup fs.
This patch reorders operations inside cgroup_mkdir() so that interface
directory and file handling comes after internal object
initialization. This will enable further refactoring.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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Currently, whether a css (cgroup_subsys_state) has its interface files
created is not tracked and assumed to change together with the owning
cgroup's lifecycle. cgroup directory and interface creation is being
separated out from internal object creation to help refactoring and
eventually allow cgroups which are not visible through cgroupfs.
This patch adds CSS_VISIBLE to track whether a css has its interface
files created and perform management operations only when necessary
which helps decoupling interface file handling from internal object
lifecycle. After this patch, all css interface file management
functions can be called regardless of the current state and will
achieve the expected result.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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Currently, interface files are created when a css is created depending
on whether @visible is set. This patch separates out the two into
separate steps to help code refactoring and eventually allow cgroups
which aren't visible through cgroup fs.
Move css_populate_dir() out of create_css() and drop @visible. While
at it, rename the function to css_create() for consistency.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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During task migration, tasks may transfer between two css_sets which
are associated with the same cgroup. If those tasks are the only
tasks in the cgroup, this currently triggers a spurious de-populated
event on the cgroup.
Fix it by bumping up populated count before bumping it down during
migration to ensure that it doesn't reach zero spuriously.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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css_sets are hashed by their subsys[] contents and in cgroup_init()
init_css_set is hashed early, before subsystem inits, when all entries
in its subsys[] are NULL, so that cgroup_dfl_root initialization can
find and link to it. As subsystems are initialized,
init_css_set.subsys[] is filled up but the hashing is never updated
making init_css_set hashed in the wrong place. While incorrect, this
doesn't cause a critical failure as css_set management code would
create an identical css_set dynamically.
Fix it by rehashing init_css_set after subsystems are initialized.
While at it, drop unnecessary @key local variable.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
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Revert commits:
a6e707ddbdf1: KVM: arm/arm64: timer: Switch to CLOCK_MONOTONIC_RAW
9006a01829a5: hrtimer: Catch illegal clockids
9c808765e88e: hrtimer: Add support for CLOCK_MONOTONIC_RAW
Marc found out, that there are fundamental issues with that patch series
because __hrtimer_get_next_event() and hrtimer_forward() need support for
CLOCK_MONOTONIC_RAW. Nothing which is easily fixed, so revert the whole lot.
Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/56D6CEF0.8060607@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Paul noticed that the conversion of the death reporting introduced a race
where the outgoing cpu might be delayed after waking the controll processor,
so it might not be able to call rcu_report_dead() before being physically
removed, leading to RCU stalls.
We cant call complete after rcu_report_dead(), so instead of going back to
busy polling, simply issue a function call to do the completion.
Fixes: 27d50c7eeb0f "rcu: Make CPU_DYING_IDLE an explicit call"
Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20160302201127.GA23440@linux.vnet.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
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Another representative use case of time sync and the correlated
clocksource (in addition to PTP noted above) is PTP synchronized
audio.
In a streaming application, as an example, samples will be sent and/or
received by multiple devices with a presentation time that is in terms
of the PTP master clock. Synchronizing the audio output on these
devices requires correlating the audio clock with the PTP master
clock. The more precise this correlation is, the better the audio
quality (i.e. out of sync audio sounds bad).
From an application standpoint, to correlate the PTP master clock with
the audio device clock, the system clock is used as a intermediate
timebase. The transforms such an application would perform are:
System Clock <-> Audio clock
System Clock <-> Network Device Clock [<-> PTP Master Clock]
Modern Intel platforms can perform a more accurate cross timestamp in
hardware (ART,audio device clock). The audio driver requires
ART->system time transforms -- the same as required for the network
driver. These platforms offload audio processing (including
cross-timestamps) to a DSP which to ensure uninterrupted audio
processing, communicates and response to the host only once every
millsecond. As a result is takes up to a millisecond for the DSP to
receive a request, the request is processed by the DSP, the audio
output hardware is polled for completion, the result is copied into
shared memory, and the host is notified. All of these operation occur
on a millisecond cadence. This transaction requires about 2 ms, but
under heavier workloads it may take up to 4 ms.
Adding a history allows these slow devices the option of providing an
ART value outside of the current interval. In this case, the callback
provided is an accessor function for the previously obtained counter
value. If get_system_device_crosststamp() receives a counter value
previous to cycle_last, it consults the history provided as an
argument in history_ref and interpolates the realtime and monotonic
raw system time using the provided counter value. If there are any
clock discontinuities, e.g. from calling settimeofday(), the monotonic
raw time is interpolated in the usual way, but the realtime clock time
is adjusted by scaling the monotonic raw adjustment.
When an accessor function is used a history argument *must* be
provided. The history is initialized using ktime_get_snapshot() and
must be called before the counter values are read.
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: kevin.b.stanton@intel.com
Cc: kevin.j.clarke@intel.com
Cc: hpa@zytor.com
Cc: jeffrey.t.kirsher@intel.com
Cc: netdev@vger.kernel.org
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com>
[jstultz: Fixed up cycles_t/cycle_t type confusion]
Signed-off-by: John Stultz <john.stultz@linaro.org>
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synchronization
ACKNOWLEDGMENT: cross timestamp code was developed by Thomas Gleixner
<tglx@linutronix.de>. It has changed considerably and any mistakes are
mine.
The precision with which events on multiple networked systems can be
synchronized using, as an example, PTP (IEEE 1588, 802.1AS) is limited
by the precision of the cross timestamps between the system clock and
the device (timestamp) clock. Precision here is the degree of
simultaneity when capturing the cross timestamp.
Currently the PTP cross timestamp is captured in software using the
PTP device driver ioctl PTP_SYS_OFFSET. Reads of the device clock are
interleaved with reads of the realtime clock. At best, the precision
of this cross timestamp is on the order of several microseconds due to
software latencies. Sub-microsecond precision is required for
industrial control and some media applications. To achieve this level
of precision hardware supported cross timestamping is needed.
The function get_device_system_crosstimestamp() allows device drivers
to return a cross timestamp with system time properly scaled to
nanoseconds. The realtime value is needed to discipline that clock
using PTP and the monotonic raw value is used for applications that
don't require a "real" time, but need an unadjusted clock time. The
get_device_system_crosstimestamp() code calls back into the driver to
ensure that the system counter is within the current timekeeping
update interval.
Modern Intel hardware provides an Always Running Timer (ART) which is
exactly related to TSC through a known frequency ratio. The ART is
routed to devices on the system and is used to precisely and
simultaneously capture the device clock with the ART.
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: kevin.b.stanton@intel.com
Cc: kevin.j.clarke@intel.com
Cc: hpa@zytor.com
Cc: jeffrey.t.kirsher@intel.com
Cc: netdev@vger.kernel.org
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com>
[jstultz: Reworked to remove extra structures and simplify calling]
Signed-off-by: John Stultz <john.stultz@linaro.org>
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The code in ktime_get_snapshot() is a superset of the code in
ktime_get_raw_and_real() code. Further, ktime_get_raw_and_real() is
called only by the PPS code, pps_get_ts(). Consolidate the
pps_get_ts() code into a single function calling ktime_get_snapshot()
and eliminate ktime_get_raw_and_real(). A side effect of this is that
the raw and real results of pps_get_ts() correspond to exactly the
same clock cycle. Previously these values represented separate reads
of the system clock.
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: kevin.b.stanton@intel.com
Cc: kevin.j.clarke@intel.com
Cc: hpa@zytor.com
Cc: jeffrey.t.kirsher@intel.com
Cc: netdev@vger.kernel.org
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
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In the current timekeeping code there isn't any interface to
atomically capture the current relationship between the system counter
and system time. ktime_get_snapshot() returns this triple (counter,
monotonic raw, realtime) in the system_time_snapshot struct.
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: kevin.b.stanton@intel.com
Cc: kevin.j.clarke@intel.com
Cc: hpa@zytor.com
Cc: jeffrey.t.kirsher@intel.com
Cc: netdev@vger.kernel.org
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com>
[jstultz: Moved structure definitions around to clean things up,
fixed cycles_t/cycle_t confusion.]
Signed-off-by: John Stultz <john.stultz@linaro.org>
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The timekeeping code does not currently provide a way to translate
externally provided clocksource cycles to system time. The cycle count
is always provided by the result clocksource read() method internal to
the timekeeping code. The added function timekeeping_cycles_to_ns()
calculated a nanosecond value from a cycle count that can be added to
tk_read_base.base value yielding the current system time. This allows
clocksource cycle values external to the timekeeping code to provide a
cycle count that can be transformed to system time.
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: kevin.b.stanton@intel.com
Cc: kevin.j.clarke@intel.com
Cc: hpa@zytor.com
Cc: jeffrey.t.kirsher@intel.com
Cc: netdev@vger.kernel.org
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
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