From: Peter Xu <peterx@redhat.com>
To: Daniel Wagner <wagi@monom.org>
Cc: linux-rt-users@vger.kernel.org, John Kacur <jkacur@redhat.com>,
Clark Williams <williams@redhat.com>,
Daniel Wagner <dwagner@suse.de>
Subject: Re: [PATCH] rt-tests: Drop use_current_cpuset() check
Date: Wed, 17 Mar 2021 08:51:47 -0400 [thread overview]
Message-ID: <20210317125147.GH395976@xz-x1> (raw)
In-Reply-To: <20210317074903.5lskayjwylnvuhks@beryllium.lan>
Hi, Daniel,
On Wed, Mar 17, 2021 at 08:49:03AM +0100, Daniel Wagner wrote:
> On Tue, Mar 16, 2021 at 04:07:05PM -0400, Peter Xu wrote:
> > I think what I'm missing is why we had such a restriction. Quotting from the
> > commit ID:
>
> IIRC, the current behavior allows the process to be placed into a cgroup
> with a subset of CPUs and you just can do 'cyclictest -a -t'. Process
> should not ignore external configuration. That's my whole point here.
In that case again I think a sane solution is not to check the cpu list in
every single tool we use, because even if we do that for all tools in rt-teets
repo, we can't guarantee to have this check for the rest tools to not ignore
this restriction.
A simple example is: what if the user specified "taskset -c $CPU cyclictest -a
$CPU -t 1 ..." where $CPU is not in the allowed list of current bash? As long
as the taskset would work the so-called "environment" will be changed before
even loading cyclictest.
If you see that's the point I said we should fail at the same check point of
sched_setaffinity() rather than checking it explicitly in the tool, because
if we want a real-world restriction that's the only place I think it's possible..
But I'm not a cgroup/container guy, please correct me if I understood.
--
Peter Xu
next prev parent reply other threads:[~2021-03-17 12:52 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-15 19:37 [PATCH] rt-tests: Drop use_current_cpuset() check Peter Xu
2021-03-16 8:18 ` Daniel Wagner
2021-03-16 20:07 ` Peter Xu
2021-03-17 7:49 ` Daniel Wagner
2021-03-17 12:51 ` Peter Xu [this message]
2021-03-17 15:08 ` John Kacur
2021-03-17 15:21 ` Peter Xu
2021-03-17 15:47 ` John Kacur
2021-03-17 17:20 ` Daniel Wagner
2021-03-17 16:40 ` Ahmed S. Darwish
2021-03-17 17:15 ` Daniel Wagner
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