linux-stable.git/kernel/sched/psi.c, branch v6.0

sched/psi: Remove unused parameter nbytes of psi_trigger_create()

2022-08-15T22:35:25+00:00

psi_trigger_create()'s 'nbytes' parameter is not used, so we can remove it.

Signed-off-by: Hao Jia 
Reviewed-by: Ingo Molnar 
Acked-by: Johannes Weiner 
Signed-off-by: Tejun Heo

sched/psi: Zero the memory of struct psi_group

2022-08-15T22:35:13+00:00

After commit 5f69a6577bc3 ("psi: dont alloc memory for psi by default"),
the memory used by struct psi_group is no longer allocated and zeroed
in cgroup_create().

Since the memory of struct psi_group is not zeroed, the data in this
memory is random, which will lead to inaccurate psi statistics when
creating a new cgroup.

So we use kzlloc() to allocate and zero the struct psi_group and
remove the redundant zeroing in group_init().

Steps to reproduce:
1. Use cgroup v2 and enable CONFIG_PSI
2. Create a new cgroup, and query psi statistics
mkdir /sys/fs/cgroup/test
cat /sys/fs/cgroup/test/cpu.pressure
some avg10=0.00 avg60=0.00 avg300=47927752200.00 total=12884901
full avg10=561815124.00 avg60=125835394188.00 avg300=1077090462000.00 total=10273561772

cat /sys/fs/cgroup/test/io.pressure
some avg10=1040093132823.95 avg60=1203770351379.21 avg300=3862252669559.46 total=4294967296
full avg10=921884564601.39 avg60=0.00 avg300=1984507298.35 total=442381631

cat /sys/fs/cgroup/test/memory.pressure
some avg10=232476085778.11 avg60=0.00 avg300=0.00 total=0
full avg10=0.00 avg60=0.00 avg300=2585658472280.57 total=12884901

Fixes: commit 5f69a6577bc3 ("psi: dont alloc memory for psi by default")
Signed-off-by: Hao Jia 
Reviewed-by: Ingo Molnar 
Acked-by: Johannes Weiner 
Signed-off-by: Tejun Heo

psi: dont alloc memory for psi by default

2022-06-07T17:11:47+00:00

Memory about struct psi_group is allocated by default for
each cgroup even if psi_disabled is true, in this case, these
allocated memory is waste, so alloc memory for struct psi_group
only when psi_disabled is false.

Signed-off-by: Chen Wandun 
Acked-by: Johannes Weiner 
Signed-off-by: Tejun Heo

sched/psi: report zeroes for CPU full at the system level

2022-04-22T10:14:08+00:00

Martin find it confusing when look at the /proc/pressure/cpu output,
and found no hint about that CPU "full" line in psi Documentation.

% cat /proc/pressure/cpu
some avg10=0.92 avg60=0.91 avg300=0.73 total=933490489
full avg10=0.22 avg60=0.23 avg300=0.16 total=358783277

The PSI_CPU_FULL state is introduced by commit e7fcd7622823
("psi: Add PSI_CPU_FULL state"), which mainly for cgroup level,
but also counted at the system level as a side effect.

Naturally, the FULL state doesn't exist for the CPU resource at
the system level. These "full" numbers can come from CPU idle
schedule latency. For example, t1 is the time when task wakeup
on an idle CPU, t2 is the time when CPU pick and switch to it.
The delta of (t2 - t1) will be in CPU_FULL state.

Another case all processes can be stalled is when all cgroups
have been throttled at the same time, which unlikely to happen.

Anyway, CPU_FULL metric is meaningless and confusing at the
system level. So this patch will report zeroes for CPU full
at the system level, and update psi Documentation accordingly.

Fixes: e7fcd7622823 ("psi: Add PSI_CPU_FULL state")
Reported-by: Martin Steigerwald 
Suggested-by: Johannes Weiner 
Signed-off-by: Chengming Zhou 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Johannes Weiner 
Link: https://lore.kernel.org/r/20220408121914.82855-1-zhouchengming@bytedance.com

psi: Fix trigger being fired unexpectedly at initial

2022-04-22T10:14:06+00:00

When a trigger being created, its win.start_value and win.start_time are
reset to zero. If group->total[PSI_POLL][t->state] has accumulated before,
this trigger will be fired unexpectedly in the next period, even if its
growth time does not reach its threshold.

So set the window of the new trigger to the current state value.

Signed-off-by: Hailong Liu 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Suren Baghdasaryan 
Link: https://lore.kernel.org/r/1648789811-3788971-1-git-send-email-liuhailong@linux.alibaba.com

sched/headers: Introduce kernel/sched/build_utility.c and build multiple .c files there

2022-02-23T09:58:33+00:00

Collect all utility functionality source code files into a single kernel/sched/build_utility.c file,
via #include-ing the .c files:

    kernel/sched/clock.c
    kernel/sched/completion.c
    kernel/sched/loadavg.c
    kernel/sched/swait.c
    kernel/sched/wait_bit.c
    kernel/sched/wait.c

CONFIG_CPU_FREQ:
    kernel/sched/cpufreq.c

CONFIG_CPU_FREQ_GOV_SCHEDUTIL:
    kernel/sched/cpufreq_schedutil.c

CONFIG_CGROUP_CPUACCT:
    kernel/sched/cpuacct.c

CONFIG_SCHED_DEBUG:
    kernel/sched/debug.c

CONFIG_SCHEDSTATS:
    kernel/sched/stats.c

CONFIG_SMP:
   kernel/sched/cpupri.c
   kernel/sched/stop_task.c
   kernel/sched/topology.c

CONFIG_SCHED_CORE:
   kernel/sched/core_sched.c

CONFIG_PSI:
   kernel/sched/psi.c

CONFIG_MEMBARRIER:
   kernel/sched/membarrier.c

CONFIG_CPU_ISOLATION:
   kernel/sched/isolation.c

CONFIG_SCHED_AUTOGROUP:
   kernel/sched/autogroup.c

The goal is to amortize the 60+ KLOC header bloat from over a dozen build units into
a single build unit.

The build time of build_utility.c also roughly matches the build time of core.c and
fair.c - allowing better load-balancing of scheduler-only rebuilds.

Signed-off-by: Ingo Molnar 
Reviewed-by: Peter Zijlstra

Merge tag 'v5.17-rc5' into sched/core, to resolve conflicts

2022-02-21T10:53:51+00:00

New conflicts in sched/core due to the following upstream fixes:

  44585f7bc0cb ("psi: fix "defined but not used" warnings when CONFIG_PROC_FS=n")
  a06247c6804f ("psi: Fix uaf issue when psi trigger is destroyed while being polled")

Conflicts:
	include/linux/psi_types.h
	kernel/sched/psi.c

Signed-off-by: Ingo Molnar

psi: fix possible trigger missing in the window

2022-02-16T14:57:54+00:00

When a new threshold breaching stall happens after a psi event was
generated and within the window duration, the new event is not
generated because the events are rate-limited to one per window. If
after that no new stall is recorded then the event will not be
generated even after rate-limiting duration has passed. This is
happening because with no new stall, window_update will not be called
even though threshold was previously breached. To fix this, record
threshold breaching occurrence and generate the event once window
duration is passed.

Suggested-by: Suren Baghdasaryan 
Signed-off-by: Zhaoyang Huang 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Johannes Weiner 
Acked-by: Suren Baghdasaryan 
Link: https://lore.kernel.org/r/1643093818-19835-1-git-send-email-huangzhaoyang@gmail.com

psi: fix "defined but not used" warnings when CONFIG_PROC_FS=n

2022-01-30T07:56:58+00:00

When CONFIG_PROC_FS is disabled psi code generates the following
warnings:

  kernel/sched/psi.c:1364:30: warning: 'psi_cpu_proc_ops' defined but not used [-Wunused-const-variable=]
      1364 | static const struct proc_ops psi_cpu_proc_ops = {
           |                              ^~~~~~~~~~~~~~~~
  kernel/sched/psi.c:1355:30: warning: 'psi_memory_proc_ops' defined but not used [-Wunused-const-variable=]
      1355 | static const struct proc_ops psi_memory_proc_ops = {
           |                              ^~~~~~~~~~~~~~~~~~~
  kernel/sched/psi.c:1346:30: warning: 'psi_io_proc_ops' defined but not used [-Wunused-const-variable=]
      1346 | static const struct proc_ops psi_io_proc_ops = {
           |                              ^~~~~~~~~~~~~~~

Make definitions of these structures and related functions conditional
on CONFIG_PROC_FS config.

Link: https://lkml.kernel.org/r/20220119223940.787748-3-surenb@google.com
Fixes: 0e94682b73bf ("psi: introduce psi monitor")
Signed-off-by: Suren Baghdasaryan 
Reported-by: kernel test robot 
Acked-by: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

psi: Fix "defined but not used" warnings when CONFIG_PROC_FS=n

2022-01-27T11:57:19+00:00

When CONFIG_PROC_FS is disabled psi code generates the following warnings:

kernel/sched/psi.c:1364:30: warning: 'psi_cpu_proc_ops' defined but not used [-Wunused-const-variable=]
    1364 | static const struct proc_ops psi_cpu_proc_ops = {
         |                              ^~~~~~~~~~~~~~~~
kernel/sched/psi.c:1355:30: warning: 'psi_memory_proc_ops' defined but not used [-Wunused-const-variable=]
    1355 | static const struct proc_ops psi_memory_proc_ops = {
         |                              ^~~~~~~~~~~~~~~~~~~
kernel/sched/psi.c:1346:30: warning: 'psi_io_proc_ops' defined but not used [-Wunused-const-variable=]
    1346 | static const struct proc_ops psi_io_proc_ops = {
         |                              ^~~~~~~~~~~~~~~

Make definitions of these structures and related functions conditional on
CONFIG_PROC_FS config.

Fixes: 0e94682b73bf ("psi: introduce psi monitor")
Reported-by: kernel test robot 
Signed-off-by: Suren Baghdasaryan 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20220119223940.787748-3-surenb@google.com