linux-stable.git/kernel/sched, branch v5.9.8

cpufreq: schedutil: Always call driver if CPUFREQ_NEED_UPDATE_LIMITS is set

2020-11-05T10:51:57+00:00

commit d1e7c2996e988866e7ceceb4641a0886885b7889 upstream.

Because sugov_update_next_freq() may skip a frequency update even if
the need_freq_update flag has been set for the policy at hand, policy
limits updates may not take effect as expected.

For example, if the intel_pstate driver operates in the passive mode
with HWP enabled, it needs to update the HWP min and max limits when
the policy min and max limits change, respectively, but that may not
happen if the target frequency does not change along with the limit
at hand.  In particular, if the policy min is changed first, causing
the target frequency to be adjusted to it, and the policy max limit
is changed later to the same value, the HWP max limit will not be
updated to follow it as expected, because the target frequency is
still equal to the policy min limit and it will not change until
that limit is updated.

To address this issue, modify get_next_freq() to let the driver
callback run if the CPUFREQ_NEED_UPDATE_LIMITS cpufreq driver flag
is set regardless of whether or not the new frequency to set is
equal to the previous one.

Fixes: f6ebbcf08f37 ("cpufreq: intel_pstate: Implement passive mode with HWP enabled")
Reported-by: Zhang Rui 
Tested-by: Zhang Rui 
Cc: 5.9+  # 5.9+: 1c534352f47f cpufreq: Introduce CPUFREQ_NEED_UPDATE_LIMITS ...
Cc: 5.9+  # 5.9+: a62f68f5ca53 cpufreq: Introduce cpufreq_driver_test_flags()
Signed-off-by: Rafael J. Wysocki 
Acked-by: Viresh Kumar 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

sched/features: Fix !CONFIG_JUMP_LABEL case

2020-10-29T09:12:07+00:00

[ Upstream commit a73f863af4ce9730795eab7097fb2102e6854365 ]

Commit:

  765cc3a4b224e ("sched/core: Optimize sched_feat() for !CONFIG_SCHED_DEBUG builds")

made sched features static for !CONFIG_SCHED_DEBUG configurations, but
overlooked the CONFIG_SCHED_DEBUG=y and !CONFIG_JUMP_LABEL cases.

For the latter echoing changes to /sys/kernel/debug/sched_features has
the nasty effect of effectively changing what sched_features reports,
but without actually changing the scheduler behaviour (since different
translation units get different sysctl_sched_features).

Fix CONFIG_SCHED_DEBUG=y and !CONFIG_JUMP_LABEL configurations by properly
restructuring ifdefs.

Fixes: 765cc3a4b224e ("sched/core: Optimize sched_feat() for !CONFIG_SCHED_DEBUG builds")
Co-developed-by: Daniel Bristot de Oliveira 
Signed-off-by: Daniel Bristot de Oliveira 
Signed-off-by: Juri Lelli 
Signed-off-by: Ingo Molnar 
Acked-by: Patrick Bellasi 
Reviewed-by: Valentin Schneider 
Link: https://lore.kernel.org/r/20201013053114.160628-1-juri.lelli@redhat.com
Signed-off-by: Sasha Levin

sched/fair: Use dst group while checking imbalance for NUMA balancer

2020-10-29T09:11:01+00:00

[ Upstream commit 233e7aca4c8a2c764f556bba9644c36154017e7f ]

Barry Song noted the following

	Something is wrong. In find_busiest_group(), we are checking if
	src has higher load, however, in task_numa_find_cpu(), we are
	checking if dst will have higher load after balancing. It seems
	it is not sensible to check src.

	It maybe cause wrong imbalance value, for example,

	if dst_running = env->dst_stats.nr_running + 1 results in 3 or
	above, and src_running = env->src_stats.nr_running - 1 results
	in 1;

	The current code is thinking imbalance as 0 since src_running is
	smaller than 2.  This is inconsistent with load balancer.

Basically, in find_busiest_group(), the NUMA imbalance is ignored if moving
a task "from an almost idle domain" to a "domain with spare capacity". This
patch forbids movement "from a misplaced domain" to "an almost idle domain"
as that is closer to what the CPU load balancer expects.

This patch is not a universal win. The old behaviour was intended to allow
a task from an almost idle NUMA node to migrate to its preferred node if
the destination had capacity but there are corner cases.  For example,
a NAS compute load could be parallelised to use 1/3rd of available CPUs
but not all those potential tasks are active at all times allowing this
logic to trigger. An obvious example is specjbb 2005 running various
numbers of warehouses on a 2 socket box with 80 cpus.

specjbb
                               5.9.0-rc4              5.9.0-rc4
                                 vanilla        dstbalance-v1r1
Hmean     tput-1     46425.00 (   0.00%)    43394.00 *  -6.53%*
Hmean     tput-2     98416.00 (   0.00%)    96031.00 *  -2.42%*
Hmean     tput-3    150184.00 (   0.00%)   148783.00 *  -0.93%*
Hmean     tput-4    200683.00 (   0.00%)   197906.00 *  -1.38%*
Hmean     tput-5    236305.00 (   0.00%)   245549.00 *   3.91%*
Hmean     tput-6    281559.00 (   0.00%)   285692.00 *   1.47%*
Hmean     tput-7    338558.00 (   0.00%)   334467.00 *  -1.21%*
Hmean     tput-8    340745.00 (   0.00%)   372501.00 *   9.32%*
Hmean     tput-9    424343.00 (   0.00%)   413006.00 *  -2.67%*
Hmean     tput-10   421854.00 (   0.00%)   434261.00 *   2.94%*
Hmean     tput-11   493256.00 (   0.00%)   485330.00 *  -1.61%*
Hmean     tput-12   549573.00 (   0.00%)   529959.00 *  -3.57%*
Hmean     tput-13   593183.00 (   0.00%)   555010.00 *  -6.44%*
Hmean     tput-14   588252.00 (   0.00%)   599166.00 *   1.86%*
Hmean     tput-15   623065.00 (   0.00%)   642713.00 *   3.15%*
Hmean     tput-16   703924.00 (   0.00%)   660758.00 *  -6.13%*
Hmean     tput-17   666023.00 (   0.00%)   697675.00 *   4.75%*
Hmean     tput-18   761502.00 (   0.00%)   758360.00 *  -0.41%*
Hmean     tput-19   796088.00 (   0.00%)   798368.00 *   0.29%*
Hmean     tput-20   733564.00 (   0.00%)   823086.00 *  12.20%*
Hmean     tput-21   840980.00 (   0.00%)   856711.00 *   1.87%*
Hmean     tput-22   804285.00 (   0.00%)   872238.00 *   8.45%*
Hmean     tput-23   795208.00 (   0.00%)   889374.00 *  11.84%*
Hmean     tput-24   848619.00 (   0.00%)   966783.00 *  13.92%*
Hmean     tput-25   750848.00 (   0.00%)   903790.00 *  20.37%*
Hmean     tput-26   780523.00 (   0.00%)   962254.00 *  23.28%*
Hmean     tput-27  1042245.00 (   0.00%)   991544.00 *  -4.86%*
Hmean     tput-28  1090580.00 (   0.00%)  1035926.00 *  -5.01%*
Hmean     tput-29   999483.00 (   0.00%)  1082948.00 *   8.35%*
Hmean     tput-30  1098663.00 (   0.00%)  1113427.00 *   1.34%*
Hmean     tput-31  1125671.00 (   0.00%)  1134175.00 *   0.76%*
Hmean     tput-32   968167.00 (   0.00%)  1250286.00 *  29.14%*
Hmean     tput-33  1077676.00 (   0.00%)  1060893.00 *  -1.56%*
Hmean     tput-34  1090538.00 (   0.00%)  1090933.00 *   0.04%*
Hmean     tput-35   967058.00 (   0.00%)  1107421.00 *  14.51%*
Hmean     tput-36  1051745.00 (   0.00%)  1210663.00 *  15.11%*
Hmean     tput-37  1019465.00 (   0.00%)  1351446.00 *  32.56%*
Hmean     tput-38  1083102.00 (   0.00%)  1064541.00 *  -1.71%*
Hmean     tput-39  1232990.00 (   0.00%)  1303623.00 *   5.73%*
Hmean     tput-40  1175542.00 (   0.00%)  1340943.00 *  14.07%*
Hmean     tput-41  1127826.00 (   0.00%)  1339492.00 *  18.77%*
Hmean     tput-42  1198313.00 (   0.00%)  1411023.00 *  17.75%*
Hmean     tput-43  1163733.00 (   0.00%)  1228253.00 *   5.54%*
Hmean     tput-44  1305562.00 (   0.00%)  1357886.00 *   4.01%*
Hmean     tput-45  1326752.00 (   0.00%)  1406061.00 *   5.98%*
Hmean     tput-46  1339424.00 (   0.00%)  1418451.00 *   5.90%*
Hmean     tput-47  1415057.00 (   0.00%)  1381570.00 *  -2.37%*
Hmean     tput-48  1392003.00 (   0.00%)  1421167.00 *   2.10%*
Hmean     tput-49  1408374.00 (   0.00%)  1418659.00 *   0.73%*
Hmean     tput-50  1359822.00 (   0.00%)  1391070.00 *   2.30%*
Hmean     tput-51  1414246.00 (   0.00%)  1392679.00 *  -1.52%*
Hmean     tput-52  1432352.00 (   0.00%)  1354020.00 *  -5.47%*
Hmean     tput-53  1387563.00 (   0.00%)  1409563.00 *   1.59%*
Hmean     tput-54  1406420.00 (   0.00%)  1388711.00 *  -1.26%*
Hmean     tput-55  1438804.00 (   0.00%)  1387472.00 *  -3.57%*
Hmean     tput-56  1399465.00 (   0.00%)  1400296.00 *   0.06%*
Hmean     tput-57  1428132.00 (   0.00%)  1396399.00 *  -2.22%*
Hmean     tput-58  1432385.00 (   0.00%)  1386253.00 *  -3.22%*
Hmean     tput-59  1421612.00 (   0.00%)  1371416.00 *  -3.53%*
Hmean     tput-60  1429423.00 (   0.00%)  1389412.00 *  -2.80%*
Hmean     tput-61  1396230.00 (   0.00%)  1351122.00 *  -3.23%*
Hmean     tput-62  1418396.00 (   0.00%)  1383098.00 *  -2.49%*
Hmean     tput-63  1409918.00 (   0.00%)  1374662.00 *  -2.50%*
Hmean     tput-64  1410236.00 (   0.00%)  1376216.00 *  -2.41%*
Hmean     tput-65  1396405.00 (   0.00%)  1364418.00 *  -2.29%*
Hmean     tput-66  1395975.00 (   0.00%)  1357326.00 *  -2.77%*
Hmean     tput-67  1392986.00 (   0.00%)  1349642.00 *  -3.11%*
Hmean     tput-68  1386541.00 (   0.00%)  1343261.00 *  -3.12%*
Hmean     tput-69  1374407.00 (   0.00%)  1342588.00 *  -2.32%*
Hmean     tput-70  1377513.00 (   0.00%)  1334654.00 *  -3.11%*
Hmean     tput-71  1369319.00 (   0.00%)  1334952.00 *  -2.51%*
Hmean     tput-72  1354635.00 (   0.00%)  1329005.00 *  -1.89%*
Hmean     tput-73  1350933.00 (   0.00%)  1318942.00 *  -2.37%*
Hmean     tput-74  1351714.00 (   0.00%)  1316347.00 *  -2.62%*
Hmean     tput-75  1352198.00 (   0.00%)  1309974.00 *  -3.12%*
Hmean     tput-76  1349490.00 (   0.00%)  1286064.00 *  -4.70%*
Hmean     tput-77  1336131.00 (   0.00%)  1303684.00 *  -2.43%*
Hmean     tput-78  1308896.00 (   0.00%)  1271024.00 *  -2.89%*
Hmean     tput-79  1326703.00 (   0.00%)  1290862.00 *  -2.70%*
Hmean     tput-80  1336199.00 (   0.00%)  1291629.00 *  -3.34%*

The performance at the mid-point is better but not universally better. The
patch is a mixed bag depending on the workload, machine and overall
levels of utilisation. Sometimes it's better (sometimes much better),
other times it is worse (sometimes much worse). Given that there isn't a
universally good decision in this section and more people seem to prefer
the patch then it may be best to keep the LB decisions consistent and
revisit imbalance handling when the load balancer code changes settle down.

Jirka Hladky added the following observation.

	Our results are mostly in line with what you see. We observe
	big gains (20-50%) when the system is loaded to 1/3 of the
	maximum capacity and mixed results at the full load - some
	workloads benefit from the patch at the full load, others not,
	but performance changes at the full load are mostly within the
	noise of results (+/-5%). Overall, we think this patch is helpful.

[mgorman@techsingularity.net: Rewrote changelog]
Fixes: fb86f5b211 ("sched/numa: Use similar logic to the load balancer for moving between domains with spare capacity")
Signed-off-by: Barry Song 
Signed-off-by: Mel Gorman 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20200921221849.GI3179@techsingularity.net
Signed-off-by: Sasha Levin

sched/fair: Fix wrong cpu selecting from isolated domain

2020-10-29T09:11:01+00:00

[ Upstream commit df3cb4ea1fb63ff326488efd671ba3c39034255e ]

We've met problems that occasionally tasks with full cpumask
(e.g. by putting it into a cpuset or setting to full affinity)
were migrated to our isolated cpus in production environment.

After some analysis, we found that it is due to the current
select_idle_smt() not considering the sched_domain mask.

Steps to reproduce on my 31-CPU hyperthreads machine:
1. with boot parameter: "isolcpus=domain,2-31"
   (thread lists: 0,16 and 1,17)
2. cgcreate -g cpu:test; cgexec -g cpu:test "test_threads"
3. some threads will be migrated to the isolated cpu16~17.

Fix it by checking the valid domain mask in select_idle_smt().

Fixes: 10e2f1acd010 ("sched/core: Rewrite and improve select_idle_siblings())
Reported-by: Wetp Zhang 
Signed-off-by: Xunlei Pang 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Jiang Biao 
Reviewed-by: Vincent Guittot 
Link: https://lkml.kernel.org/r/1600930127-76857-1-git-send-email-xlpang@linux.alibaba.com
Signed-off-by: Sasha Levin

sched/fair: Fix wrong negative conversion in find_energy_efficient_cpu()

2020-10-29T09:11:00+00:00

[ Upstream commit da0777d35f47892f359c3f73ea155870bb595700 ]

In find_energy_efficient_cpu() 'cpu_cap' could be less that 'util'.
It might be because of RT, DL (so higher sched class than CFS), irq or
thermal pressure signal, which reduce the capacity value.
In such situation the result of 'cpu_cap - util' might be negative but
stored in the unsigned long. Then it might be compared with other unsigned
long when uclamp_rq_util_with() reduced the 'util' such that is passes the
fits_capacity() check.

Prevent this situation and make the arithmetic more safe.

Fixes: 1d42509e475cd ("sched/fair: Make EAS wakeup placement consider uclamp restrictions")
Signed-off-by: Lukasz Luba 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Valentin Schneider 
Link: https://lkml.kernel.org/r/20200810083004.26420-1-lukasz.luba@arm.com
Signed-off-by: Sasha Levin

Merge tag 'locking-urgent-2020-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-08-30T18:43:50+00:00

Pull locking fixes from Thomas Gleixner:
 "A set of fixes for lockdep, tracing and RCU:

   - Prevent recursion by using raw_cpu_* operations

   - Fixup the interrupt state in the cpu idle code to be consistent

   - Push rcu_idle_enter/exit() invocations deeper into the idle path so
     that the lock operations are inside the RCU watching sections

   - Move trace_cpu_idle() into generic code so it's called before RCU
     goes idle.

   - Handle raw_local_irq* vs. local_irq* operations correctly

   - Move the tracepoints out from under the lockdep recursion handling
     which turned out to be fragile and inconsistent"

* tag 'locking-urgent-2020-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  lockdep,trace: Expose tracepoints
  lockdep: Only trace IRQ edges
  mips: Implement arch_irqs_disabled()
  arm64: Implement arch_irqs_disabled()
  nds32: Implement arch_irqs_disabled()
  locking/lockdep: Cleanup
  x86/entry: Remove unused THUNKs
  cpuidle: Move trace_cpu_idle() into generic code
  cpuidle: Make CPUIDLE_FLAG_TLB_FLUSHED generic
  sched,idle,rcu: Push rcu_idle deeper into the idle path
  cpuidle: Fixup IRQ state
  lockdep: Use raw_cpu_*() for per-cpu variables

cpuidle: Move trace_cpu_idle() into generic code

2020-08-26T10:41:54+00:00

Remove trace_cpu_idle() from the arch_cpu_idle() implementations and
put it in the generic code, right before disabling RCU. Gets rid of
more trace_*_rcuidle() users.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Steven Rostedt (VMware) 
Reviewed-by: Thomas Gleixner 
Acked-by: Rafael J. Wysocki 
Tested-by: Marco Elver 
Link: https://lkml.kernel.org/r/20200821085348.428433395@infradead.org

sched,idle,rcu: Push rcu_idle deeper into the idle path

2020-08-26T10:41:53+00:00

Lots of things take locks, due to a wee bug, rcu_lockdep didn't notice
that the locking tracepoints were using RCU.

Push rcu_idle_{enter,exit}() as deep as possible into the idle paths,
this also resolves a lot of _rcuidle()/RCU_NONIDLE() usage.

Specifically, sched_clock_idle_wakeup_event() will use ktime which
will use seqlocks which will tickle lockdep, and
stop_critical_timings() uses lock.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Steven Rostedt (VMware) 
Reviewed-by: Thomas Gleixner 
Acked-by: Rafael J. Wysocki 
Tested-by: Marco Elver 
Link: https://lkml.kernel.org/r/20200821085348.310943801@infradead.org

treewide: Use fallthrough pseudo-keyword

2020-08-23T22:36:59+00:00

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva

Merge tag 'sched-urgent-2020-08-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-08-15T17:36:40+00:00

Pull scheduler fixes from Ingo Molnar:
 "Two fixes: fix a new tracepoint's output value, and fix the formatting
  of show-state syslog printouts"

* tag 'sched-urgent-2020-08-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/debug: Fix the alignment of the show-state debug output
  sched: Fix use of count for nr_running tracepoint