From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Li Zefan <lizefan@huawei.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>
Subject: [regression] cpuset: offlined CPUs removed from affinity masks
Date: Thu, 16 Jan 2020 12:41:35 -0500 (EST) [thread overview]
Message-ID: <1251528473.590671.1579196495905.JavaMail.zimbra@efficios.com> (raw)
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
next reply other threads:[~2020-01-16 17:48 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-16 17:41 Mathieu Desnoyers [this message]
2020-01-16 18:27 ` [regression] cpuset: offlined CPUs removed from affinity masks Valentin Schneider
2020-02-17 16:03 ` Mathieu Desnoyers
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1251528473.590671.1579196495905.JavaMail.zimbra@efficios.com \
--to=mathieu.desnoyers@efficios.com \
--cc=linux-kernel@vger.kernel.org \
--cc=lizefan@huawei.com \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).