From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D5C4233147 for ; Mon, 9 Dec 2024 13:11:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733749887; cv=none; b=Z+8BkqPgQMw7zE8SWplWCjYNTTuQtWevWnE4PkU7VBRzMD8Yo/LqIPO/ajmqrz3FW98RmbD2zxcyOOwsXoD2FYKehKH69gz+rxJT77AdnO+WwWRzGMjPBEAbI/Wc6onKrJdc5NoMTVQeSuVKMheHnIzuHUNXkH6VrpsrIpKa9DU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733749887; c=relaxed/simple; bh=zjBwD0aLX7o7j1/0ZqI6eThNSoLM2hlnGvxP8Y+aeQk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qb2v7F1fhfA+1VrT5Pc07JX31KiKZf9SzCcCeBdc4LBnhvtCfEI17+rXLf4r8oxllgQukWkj3460ScMuQYjb6h68OvupHq1j/UzIAsPTCb1K5VksfUxGTMj0WYtuUUL5Zht6v+CpfN7l9pMkoLH10j5AHLgvDDLMNwFtZvLjjoQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=MFIiQwxb; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MFIiQwxb" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1733749884; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=BWQY6IfLo/S/CDRVbklgCeHn2aHAFhi5zAR23hUPFQw=; b=MFIiQwxbjJsBTWVCv0jHCNuPGSzZmbgFazT7T+k1CbFkMhNR8cfH9rIu2ZwouQ5AypvUfg 1FfdKKYMXKbdG4BN3MtNNn6WTxnlI0eozVJbRclTPG9zoMNZ6SCNwGBdt85wLyvT/QQ5s/ u+hok6W3kCLtD3e5za+CTatqEE1Vugg= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-647-XGwXXF_sMmOO5I1OiVC7hA-1; Mon, 09 Dec 2024 08:11:19 -0500 X-MC-Unique: XGwXXF_sMmOO5I1OiVC7hA-1 X-Mimecast-MFC-AGG-ID: XGwXXF_sMmOO5I1OiVC7hA Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 362FB1956060; Mon, 9 Dec 2024 13:11:17 +0000 (UTC) Received: from pauld.westford.csb (unknown [10.22.88.126]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 00C783000198; Mon, 9 Dec 2024 13:11:12 +0000 (UTC) Date: Mon, 9 Dec 2024 08:11:10 -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 V2] sched/fair: Dequeue sched_delayed tasks when waking to a busy CPU Message-ID: <20241209131110.GC117639@pauld.westford.csb> References: <95ff75cacab4720bbbecd54e881bb94d97087b45.camel@gmx.de> <20241114112854.GA471026@pauld.westford.csb> <20241119113016.GB66918@pauld.westford.csb> <915eab00325f2bf608bcb2bd43665ccf663d4084.camel@gmx.de> <20241121115628.GB394828@pauld.westford.csb> <20241202162427.GB1226982@pauld.westford.csb> <9c78aebb3fdb8af68937a0301fabc3acb3e20c2d.camel@gmx.de> <20241202191252.GA1233297@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=us-ascii Content-Disposition: inline In-Reply-To: <20241202191252.GA1233297@pauld.westford.csb> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Hi Mike et al., On Mon, Dec 02, 2024 at 02:12:52PM -0500 Phil Auld wrote: > On Mon, Dec 02, 2024 at 05:55:28PM +0100 Mike Galbraith wrote: > > On Mon, 2024-12-02 at 11:24 -0500, Phil Auld wrote: > > > On Sat, Nov 23, 2024 at 09:44:40AM +0100 Mike Galbraith wrote: > > > > > > > > > > Question: did wiping off the evil leave any meaningful goodness behind? > > > > > > Is that for this patch? > > > > Yeah. Trying it on my box with your write command line didn't improve > > the confidence level either. My box has one CPU handling IRQs and > > waking pinned workers to service 8 fio instances. Patch was useless > > for that. > > > > I'll give it a try. Our "box" is multiple different boxes but the results > vary somewhat. The one I sent info about earlier in this thread is just > one of the more egregious and is the one the perf team lent me for a while. > In our testing this has the same effect as the original dequeue-when-delayed fix. It solves the randwrite issue and introduces the ~10-15% randread regression. Seems to be a real trade-off here. The same guys who benefit from spreading in one case benefit from staying put in the other... Cheers, Phil --