From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Li Zefan <lizefan@huawei.com>, Tejun Heo <tj@kernel.org>,
cgroups@vger.kernel.org
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Valentin Schneider <valentin.schneider@arm.com>
Subject: Re: [regression] cpuset: offlined CPUs removed from affinity masks
Date: Mon, 17 Feb 2020 11:03:07 -0500 (EST) [thread overview]
Message-ID: <1317969050.4131.1581955387909.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <1251528473.590671.1579196495905.JavaMail.zimbra@efficios.com>
Hi,
Adding Tejun and the cgroups mailing list in CC for this cpuset regression I
reported last month.
Thanks,
Mathieu
----- On Jan 16, 2020, at 12:41 PM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote:
> Hi,
>
> I noticed the following regression with CONFIG_CPUSET=y. Note that
> I am not using cpusets at all (only using the root cpuset I'm given
> at boot), it's just configured in. I am currently working on a 5.2.5
> kernel. I am simply combining use of taskset(1) (setting the affinity
> mask of a process) and cpu hotplug. The result is that with
> CONFIG_CPUSET=y, setting the affinity mask including an offline CPU number
> don't keep that CPU in the affinity mask, and it is never put back when the
> CPU comes back online. CONFIG_CPUSET=n behaves as expected, and puts back
> the CPU into the affinity mask reported to user-space when it comes back
> online.
>
>
> * With CONFIG_CPUSET=y (unexpected behavior):
>
> # echo 0 > /sys/devices/system/cpu/cpu1/online
>
> % taskset 0x7 ./loop &
> % taskset -p $!
> pid 1341's current affinity mask: 5
>
> # echo 1 > /sys/devices/system/cpu/cpu1/online
>
> taskset -p $!
> pid 1341's current affinity mask: 5
>
> kill $!
>
>
> * With CONFIG_CPUSET=n (expected behavior):
>
> (Offlining CPU, then start task)
>
> # echo 0 > /sys/devices/system/cpu/cpu1/online
>
> % taskset 0x7 ./loop &
> % taskset -p $!
> pid 1358's current affinity mask: 5
>
> # echo 1 > /sys/devices/system/cpu/cpu1/online
>
> taskset -p $!
> pid 1358's current affinity mask: 7
>
> kill $!
>
>
> Test system lscpu output:
>
> Architecture: x86_64
> CPU op-mode(s): 32-bit, 64-bit
> Byte Order: Little Endian
> CPU(s): 32
> On-line CPU(s) list: 0-31
> Thread(s) per core: 2
> Core(s) per socket: 8
> Socket(s): 2
> NUMA node(s): 2
> Vendor ID: GenuineIntel
> CPU family: 6
> Model: 60
> Model name: Intel Core Processor (Haswell, no TSX, IBRS)
> Stepping: 1
> CPU MHz: 2399.996
> BogoMIPS: 4799.99
> Hypervisor vendor: KVM
> Virtualization type: full
> L1d cache: 32K
> L1i cache: 32K
> L2 cache: 4096K
> NUMA node0 CPU(s): 0-7,16-23
> NUMA node1 CPU(s): 8-15,24-31
> Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
> cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx rdtscp lm constant_tsc
> rep_good nopl cpuid tsc_known_freq pni pclmulqdq ssse3 fma cx16 pcid sse4_1
> sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand
> hypervisor lahf_lm abm cpuid_fault invpcid_single pti ibrs ibpb fsgsbase bmi1
> avx2 smep bmi2 erms invpcid xsaveopt
>
>
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2020-02-17 16:03 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-16 17:41 [regression] cpuset: offlined CPUs removed from affinity masks Mathieu Desnoyers
2020-01-16 18:27 ` Valentin Schneider
2020-02-17 16:03 ` Mathieu Desnoyers [this message]
2020-02-19 15:19 ` Tejun Heo
2020-02-19 15:43 ` Mathieu Desnoyers
2020-02-19 15:47 ` Tejun Heo
2020-02-19 15:50 ` Mathieu Desnoyers
2020-02-19 15:52 ` Tejun Heo
2020-02-19 16:08 ` Mathieu Desnoyers
2020-02-19 16:12 ` Tejun Heo
2020-03-07 16:06 ` Mathieu Desnoyers
2020-03-12 18:26 ` Tejun Heo
2020-03-12 19:47 ` Mathieu Desnoyers
2020-03-24 18:01 ` Tejun Heo
2020-03-24 19:30 ` Mathieu Desnoyers
2020-03-30 19:53 ` Mathieu Desnoyers
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