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Thu, 21 Nov 2024 07:07:13 -0500 X-MC-Unique: vdqdNoU_N3mDIFLrhrAsRg-1 X-Mimecast-MFC-AGG-ID: vdqdNoU_N3mDIFLrhrAsRg Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E1DBB1955F77; Thu, 21 Nov 2024 12:07:10 +0000 (UTC) Received: from pauld.westford.csb (unknown [10.22.80.137]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0295A195607C; Thu, 21 Nov 2024 12:07:06 +0000 (UTC) Date: Thu, 21 Nov 2024 07:07:04 -0500 From: Phil Auld To: Mike Galbraith Cc: Peter Zijlstra , mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org, kprateek.nayak@amd.com, wuyun.abel@bytedance.com, youssefesmat@chromium.org, tglx@linutronix.de Subject: Re: [PATCH] sched/fair: Dequeue sched_delayed tasks when waking to a busy CPU Message-ID: <20241121120704.GC394828@pauld.westford.csb> References: <20241112124117.GA336451@pauld.westford.csb> <0befc9ed8979594d790a8d4fe7ff5c5534c61c3c.camel@gmx.de> <20241112154140.GC336451@pauld.westford.csb> <81de2f710d8922a47364632335ff5ba1a45625b3.camel@gmx.de> <95ff75cacab4720bbbecd54e881bb94d97087b45.camel@gmx.de> <20241114112854.GA471026@pauld.westford.csb> <20241119113016.GB66918@pauld.westford.csb> <915eab00325f2bf608bcb2bd43665ccf663d4084.camel@gmx.de> <20241121115628.GB394828@pauld.westford.csb> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241121115628.GB394828@pauld.westford.csb> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 On Thu, Nov 21, 2024 at 06:56:28AM -0500 Phil Auld wrote: > On Wed, Nov 20, 2024 at 07:37:39PM +0100 Mike Galbraith wrote: > > On Tue, 2024-11-19 at 12:51 +0100, Mike Galbraith wrote: > > > On Tue, 2024-11-19 at 06:30 -0500, Phil Auld wrote: > > > > > > > > This, below, by itself, did not do help and caused a small slowdown on some > > > > other tests.  Did this need to be on top of the wakeup change? > > > > > > No, that made a mess. > > > > Rashly speculating that turning mobile kthread component loose is what > > helped your write regression... > > > > You could try adding (p->flags & PF_KTHREAD) to the wakeup patch to > > only turn hard working kthreads loose to try to dodge service latency. > > Seems unlikely wakeup frequency * instances would combine to shred fio > > the way turning tbench loose did. > > > > Thanks, I'll try that. > Also, fwiw, I think there is another report here https://lore.kernel.org/lkml/392209D9-5AC6-4FDE-8D84-FB8A82AD9AEF@oracle.com/ which seems to be the same thing but mis-bisected. I've asked them to try with NO_DELAY_DEQUEUE just to be sure. But it looks like a duck. Cheers, Phil --