Michael Wang
dd39eadc71
sched: Avoid scale real weight down to zero ...
[ Upstream commit 26cf52229efc87e2effa9d788f9b33c40fb3358a ]
During our testing, we found a case that shares no longer
working correctly, the cgroup topology is like:
/sys/fs/cgroup/cpu/A (shares=102400)
/sys/fs/cgroup/cpu/A/B (shares=2)
/sys/fs/cgroup/cpu/A/B/C (shares=1024)
/sys/fs/cgroup/cpu/D (shares=1024)
/sys/fs/cgroup/cpu/D/E (shares=1024)
/sys/fs/cgroup/cpu/D/E/F (shares=1024)
The same benchmark is running in group C & F, no other tasks are
running, the benchmark is capable to consumed all the CPUs.
We suppose the group C will win more CPU resources since it could
enjoy all the shares of group A, but it's F who wins much more.
The reason is because we have group B with shares as 2, since
A->cfs_rq.load.weight == B->se.load.weight == B->shares/nr_cpus,
so A->cfs_rq.load.weight become very small.
And in calc_group_shares() we calculate shares as:
load = max(scale_load_down(cfs_rq->load.weight), cfs_rq->avg.load_avg);
shares = (tg_shares * load) / tg_weight;
Since the 'cfs_rq->load.weight' is too small, the load become 0
after scale down, although 'tg_shares' is 102400, shares of the se
which stand for group A on root cfs_rq become 2.
While the se of D on root cfs_rq is far more bigger than 2, so it
wins the battle.
Thus when scale_load_down() scale real weight down to 0, it's no
longer telling the real story, the caller will have the wrong
information and the calculation will be buggy.
This patch add check in scale_load_down(), so the real weight will
be >= MIN_SHARES after scale, after applied the group C wins as
expected.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/38e8e212-59a1-64b2-b247-b6d0b52d8dc1@linux.alibaba.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-04-17 10:50:02 +02:00
bpf: Explicitly memset some bpf info structures declared on the stack
2020-04-02 15:11:01 +02:00
cgroup1: don't call release_agent when it is ""
2020-04-01 11:01:51 +02:00
kgdb: don't use a notifier to enter kgdb at panic; call directly
2019-09-25 17:51:40 -07:00
dma-mapping: Fix dma_pgprot() for unencrypted coherent pages
2020-04-17 10:50:01 +02:00
perf/core: Fix mlock accounting in perf_mmap()
2020-02-11 04:35:54 -08:00
Revert "um: Enable CONFIG_CONSTRUCTORS"
2020-02-01 09:34:53 +00:00
genirq: Fix reference leaks on irq affinity notifiers
2020-04-01 11:02:04 +02:00
livepatch: Nullify obj->mod in klp_module_coming()'s error path
2019-08-19 13:03:37 +02:00
locking/lockdep: Fix lockdep_stats indentation problem
2020-03-05 16:43:51 +01:00
ACPI: PM: s2idle: Avoid possible race related to the EC GPE
2020-02-19 19:52:56 +01:00
printk: fix exclusive_console replaying
2020-02-24 08:36:24 +01:00
rcu: Allow only one expedited GP to run concurrently with wakeups
2020-03-05 16:43:50 +01:00
sched: Avoid scale real weight down to zero
2020-04-17 10:50:02 +02:00
time/sched_clock: Expire timer in hardirq context
2020-04-17 10:50:02 +02:00
bpf: Fix deadlock with rq_lock in bpf_send_signal()
2020-04-17 10:49:57 +02:00
audit: always check the netlink payload length in audit_receive_msg()
2020-03-05 16:43:42 +01:00
audit/stable-5.3 PR 20190702
2019-07-08 18:55:42 -07:00
audit_get_nd(): don't unlock parent too early
2019-11-10 11:56:55 -05:00
audit: fix error handling in audit_data_to_entry()
2020-03-05 16:43:42 +01:00
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500
2019-06-19 17:09:55 +02:00
kernel/configs: Replace GPL boilerplate code with SPDX identifier
2019-07-30 18:34:15 +02:00
cpu/hotplug, stop_machine: Fix stop_machine vs hotplug order
2020-02-24 08:36:23 +01:00
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 230
2019-06-19 17:09:06 +02:00
keys: Fix request_key() cache
2020-01-17 19:48:42 +01:00
kernel/elfcore.c: include proper prototypes
2019-09-25 17:51:39 -07:00
exit: panic before exit_mm() on global init exit
2020-01-09 10:20:01 +01:00
extable: Add function to search only kernel exception table
2019-08-21 22:23:48 +10:00
mm: fork: fix kernel_stack memcg stats for various stack implementations
2020-04-01 11:02:03 +02:00
Revert "libata, freezer: avoid block device removal while system is frozen"
2019-10-06 09:11:37 -06:00
futex: Unbreak futex hashing
2020-03-25 08:25:58 +01:00
kheaders: substituting --sort in archive creation
2019-10-17 09:08:19 +09:00
mm/nvdimm: add is_ioremap_addr and use that to check ioremap address
2019-07-12 11:05:40 -07:00
jump_label: Don't warn on __exit jump entries
2019-08-29 15:10:10 +01:00
kallsyms: Don't let kallsyms_lookup_size_offset() fail on retrieving the first symbol
2019-08-27 16:19:56 +01:00
sched/rt, Kconfig: Unbreak def/oldconfig with CONFIG_PREEMPT=y
2019-07-22 18:05:11 +02:00
kexec_load: Disable at runtime if the kernel is locked down
2019-08-19 21:54:15 -07:00
kexec: bail out upon SIGKILL when allocating memory.
2019-09-25 17:51:40 -07:00
kexec_elf: support 32 bit ELF files
2019-09-06 23:58:44 +02:00
Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
2019-09-28 08:14:15 -07:00
kprobes: Fix optimize_kprobe()/unoptimize_kprobe() cancellation logic
2020-03-12 13:00:09 +01:00
kthread: make __kthread_queue_delayed_work static
2019-10-16 09:20:58 -07:00
Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity
2019-09-27 19:37:27 -07:00
module: avoid setting info->name early in case we can fall back to info->mod->name
2020-02-24 08:36:54 +01:00
MODSIGN: Export module signature definitions
2019-08-05 18:39:56 -04:00
MODSIGN: Export module signature definitions
2019-08-05 18:39:56 -04:00
x86/mm: split vmalloc_sync_all()
2020-03-25 08:25:58 +01:00
padata: always acquire cpu_hotplug_lock before pinst->lock
2020-04-08 09:08:47 +02:00
panic: ensure preemption is disabled during panic()
2019-10-07 15:47:19 -07:00
lockdown: Lock down module params that specify hardware parameters (eg. ioport)
2019-08-19 21:54:16 -07:00
kernel/pid.c: convert struct pid count to refcount_t
2019-07-16 19:23:24 -07:00
proc/sysctl: add shared variables for range check
2019-07-18 17:08:07 -07:00
ptrace: reintroduce usage of subjective credentials in ptrace_has_cap()
2020-01-23 08:22:36 +01:00
mm/memory_hotplug.c: use PFN_UP / PFN_DOWN in walk_system_ram_range()
2019-09-24 15:54:09 -07:00
seccomp: Check that seccomp_notif is zeroed out by the user
2020-01-09 10:19:57 +01:00
signal: avoid double atomic counter increments for user accounting
2020-03-21 08:11:53 +01:00
smp: Warn on function calls from softirq context
2019-07-20 11:27:16 +02:00
Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2019-07-08 11:01:13 -07:00
stacktrace: Don't skip first entry on noncurrent tasks
2019-11-04 21:19:25 +01:00
stop_machine: Avoid potential race behaviour
2019-10-17 12:47:12 +02:00
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2019-09-17 12:35:15 -07:00
arch: handle arches who do not yet define clone3
2019-06-21 01:54:53 +02:00
kernel: sysctl: make drop_caches write-only
2020-01-04 19:18:32 +01:00
taskstats: fix data-race
2020-01-09 10:19:54 +01:00
torture: Remove exporting of internal functions
2019-08-01 14:30:22 -07:00
The main changes in this release include:
2019-07-18 11:51:00 -07:00
proc/sysctl: add shared variables for range check
2019-07-18 17:08:07 -07:00
smp: Remove smp_call_function() and on_each_cpu() return values
2019-06-23 14:26:26 +02:00
Keyrings namespacing
2019-07-08 19:36:47 -07:00
Keyrings namespacing
2019-07-08 19:36:47 -07:00
watchdog/softlockup: Enforce that timestamp is valid on boot
2020-02-24 08:36:52 +01:00
workqueue: don't use wq_select_unbound_cpu() for bound works
2020-03-18 07:17:50 +01:00
dd39eadc71