Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.34 as permitted sender) client-ip=23.128.96.34;
Date:   Wed, 4 Oct 2023 14:05:44 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Julia Lawall <julia.lawall@inria.fr>
Cc:     Ingo Molnar <mingo@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Mel Gorman <mgorman@suse.de>, linux-kernel@vger.kernel.org
Subject: Re: EEVDF and NUMA balancing
Message-ID: <20231004120544.GA6307@noisy.programming.kicks-ass.net>
References: <alpine.DEB.2.22.394.2310032059060.3220@hadrien>
 <20231003215159.GJ1539@noisy.programming.kicks-ass.net>
 <alpine.DEB.2.22.394.2310041358420.3108@hadrien>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <alpine.DEB.2.22.394.2310041358420.3108@hadrien>
Precedence: bulk

On Wed, Oct 04, 2023 at 02:01:26PM +0200, Julia Lawall wrote:
> 
> 
> On Tue, 3 Oct 2023, Peter Zijlstra wrote:
> 
> > On Tue, Oct 03, 2023 at 10:25:08PM +0200, Julia Lawall wrote:
> > > Is it expected that the commit e8f331bcc270 should have an impact on the
> > > frequency of NUMA balancing?
> >
> > Definitely not expected. The only effect of that commit was supposed to
> > be the runqueue order of tasks. I'll go stare at it in the morning --
> > definitely too late for critical thinking atm.
> 
> Maybe it's just randomly making a bad situation worse rather than directly
> introduing a problem.  There is a high standard deviatind in the
> performance.  Here are some results with hyperfine.  The general trends
> are reproducible.

OK,. I'm still busy trying to bring a 4 socket machine up-to-date...
gawd I hate the boot times on those machines :/

But yeah, I was thinking similar things, I really can't spot an obvious
fail in that commit.

I'll go have a poke once the darn machine is willing to submit :-)