From: Tejun Heo <tj@kernel.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Li Zefan <lizefan@huawei.com>, cgroups <cgroups@vger.kernel.org>,
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: Wed, 19 Feb 2020 10:47:40 -0500 [thread overview]
Message-ID: <20200219154740.GD698990@mtj.thefacebook.com> (raw)
In-Reply-To: <1589496945.670.1582126985824.JavaMail.zimbra@efficios.com>
On Wed, Feb 19, 2020 at 10:43:05AM -0500, Mathieu Desnoyers wrote:
> The regression I'm talking about here is that CONFIG_CPUSET=y changes the
> behavior of the sched_setaffinify system call, which existed prior to
> cpusets.
>
> sched_setaffinity should behave in the same way for kernels configured with
> CONFIG_CPUSET=y or CONFIG_CPUSET=n.
>
> The fact that cpuset decides to irreversibly change the task affinity mask
> may not be considered a regression if it has always done that, but changing
> the behavior of sched_setaffinity seems to fit the definition of a regression.
We generally use "regression" for breakages which weren't in past
versions but then appeared later. It has debugging implications
because if we know something is a regression, we generally can point
to the commit which introduced the bug either through examining the
history or bisection.
It is a silly bug, for sure, but slapping regression name on it just
confuses rather than helping anything.
--
tejun
next prev parent reply other threads:[~2020-02-19 15:47 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-16 17:41 Mathieu Desnoyers
2020-01-16 18:27 ` 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 [this message]
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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