From: Michal Hocko <mhocko@suse.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.com>,
Leonardo Bras <leobras.c@gmail.com>,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
linux-mm@kvack.org, Johannes Weiner <hannes@cmpxchg.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Shakeel Butt <shakeel.butt@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Vlastimil Babka <vbabka@suse.cz>,
Hyeonggon Yoo <42.hyeyoo@gmail.com>,
Leonardo Bras <leobras@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Waiman Long <longman@redhat.com>,
Boqun Feng <boqun.feng@gmail.com>,
Frederic Weisbecker <fweisbecker@suse.de>
Subject: Re: [PATCH 0/4] Introduce QPW for per-cpu operations
Date: Mon, 23 Feb 2026 10:11:11 +0100 [thread overview]
Message-ID: <aZwZrw_LTilXsPd4@tiehlicka> (raw)
In-Reply-To: <aZivpwJnIGKdAMYE@tpad>
On Fri 20-02-26 16:01:59, Marcelo Tosatti wrote:
> On Fri, Feb 20, 2026 at 06:58:10PM +0100, Vlastimil Babka wrote:
[...]
> > >> So if we can assume that workloads on isolated cpus make syscalls only
> > >> rarely, and when they do they can tolerate them being slower, I think the
> > >> "avoid sheaves on isolated cpus" would be the best way here.
> > >
> > > I am not sure its safe to assume that. Ask Gemini about isolcpus use
> > > cases and:
> >
> > I don't think it's answering the question about syscalls. But didn't read
> > too closely given the nature of it.
>
> People use isolcpus with all kinds of programs.
>
> > > For example, AF_XDP bypass uses system calls (and wants isolcpus):
> > >
> > > https://www.quantvps.com/blog/kernel-bypass-in-hft?srsltid=AfmBOoryeSxuuZjzTJIC9O-Ag8x4gSwjs-V4Xukm2wQpGmwDJ6t4szuE
> >
> > Didn't spot system calls mentioned TBH.
>
> I don't see why you want to reduce performance of applications that
> execute on isolcpus=, if you can avoid that.
If you can avoid that by making performance bad for everybody else then
then it seems safer to sacrifice those workloads that are much more
special - i.e. cpu isolation.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2026-02-23 9:11 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-06 14:34 Marcelo Tosatti
2026-02-06 14:34 ` [PATCH 1/4] Introducing qpw_lock() and per-cpu queue & flush work Marcelo Tosatti
2026-02-06 15:20 ` Marcelo Tosatti
2026-02-07 0:16 ` Leonardo Bras
2026-02-11 12:09 ` Marcelo Tosatti
2026-02-14 21:32 ` Leonardo Bras
2026-02-06 14:34 ` [PATCH 2/4] mm/swap: move bh draining into a separate workqueue Marcelo Tosatti
2026-02-06 14:34 ` [PATCH 3/4] swap: apply new queue_percpu_work_on() interface Marcelo Tosatti
2026-02-07 1:06 ` Leonardo Bras
2026-02-06 14:34 ` [PATCH 4/4] slub: " Marcelo Tosatti
2026-02-07 1:27 ` Leonardo Bras
2026-02-06 23:56 ` [PATCH 0/4] Introduce QPW for per-cpu operations Leonardo Bras
2026-02-10 14:01 ` Michal Hocko
2026-02-11 12:01 ` Marcelo Tosatti
2026-02-11 12:11 ` Marcelo Tosatti
2026-02-14 21:35 ` Leonardo Bras
2026-02-11 16:38 ` Michal Hocko
2026-02-11 16:50 ` Marcelo Tosatti
2026-02-11 16:59 ` Vlastimil Babka
2026-02-11 17:07 ` Michal Hocko
2026-02-14 22:02 ` Leonardo Bras
2026-02-16 11:00 ` Michal Hocko
2026-02-19 15:27 ` Marcelo Tosatti
2026-02-19 19:30 ` Michal Hocko
2026-02-20 14:30 ` Marcelo Tosatti
2026-02-23 9:18 ` Michal Hocko
2026-02-20 10:48 ` Vlastimil Babka
2026-02-20 12:31 ` Michal Hocko
2026-02-20 17:35 ` Marcelo Tosatti
2026-02-20 17:58 ` Vlastimil Babka
2026-02-20 19:01 ` Marcelo Tosatti
2026-02-23 9:11 ` Michal Hocko [this message]
2026-02-20 16:51 ` Marcelo Tosatti
2026-02-20 16:55 ` Marcelo Tosatti
2026-02-20 22:38 ` Leonardo Bras
2026-02-20 21:58 ` Leonardo Bras
2026-02-23 9:06 ` Michal Hocko
2026-02-19 13:15 ` Marcelo Tosatti
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