From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 2E35260890 for ; Fri, 22 Nov 2024 15:43:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732290181; cv=none; b=Jdl9sS28uni3kHBf+DrRyVYyOWSdPmXDXldEBaKcLxT2oqB4K3n2BiRH758qIx9WcwQq+ALEBX4zLJfn7Rf01X3WoKqznt4EINOBTeLTOWMfOgF11DaHMGeI5cHfabh7FhUFZVCe4rhT39ja50ey+e9go1ZTXiX+irlZYy+TrTA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732290181; c=relaxed/simple; bh=jtmfzGPszDdvV+y408JrBDnu/inX7FBBktOh+Pt++50=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=OSivN0RWBiACAfv8RsKNCUiP/Hnse4qHJaWCjutV1+4QZr5EMealacbJFfzK+ObadRj8VILPLvCOeaivFeRiuyWLnln20LxfN5gTEymcMUeAC6FPhzI5MHpBTaXj1f001oJEoKrSn2aTtr5IFJImYjjbtpb88XtAJmG/eaJ0bHU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=BlxwRA2E; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="BlxwRA2E" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=jtmfzGPszDdvV+y408JrBDnu/inX7FBBktOh+Pt++50=; b=BlxwRA2EbghNnNVP3/SRGvtHJt OgQQZS2ISUll+QAWKFnvtni6IT23RHpdW5XAni2KYKn20gEC1dFOHsg2afzkJMQwb5MrPlVI2fOj6 kI1mZh44F9M5VFQ7AsmLW0bdCLt5g3UgqmS3WWBgLayaJW/3+8yM62BG35q54+pxH7pO7ilraESyu uuVGrLU8vWR2lcX90YnNkh7uSrVzd45buKExu2pfuEqzAdFvEe4l86mQWOwKMbjKfhfES+NchYB82 3NiexEV2xOsp3XQZBvly+AAPsmK5i4Phhu9Y5nbZTQuhKgEfhRmKxDnf+rFvx9343P5KKuxRYSghc PInDOOdg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tEVo4-00000007xf0-28mD; Fri, 22 Nov 2024 15:42:54 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 270A030066A; Fri, 22 Nov 2024 16:42:53 +0100 (CET) Date: Fri, 22 Nov 2024 16:42:53 +0100 From: Peter Zijlstra To: Daniel Vacek Cc: Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched/fair: properly serialize the cfs_rq h_load calculation Message-ID: <20241122154253.GZ24774@noisy.programming.kicks-ass.net> References: <20241122152856.3533625-1-neelx@suse.com> 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: <20241122152856.3533625-1-neelx@suse.com> On Fri, Nov 22, 2024 at 04:28:55PM +0100, Daniel Vacek wrote: > Make sure the given cfs_rq's h_load is always correctly updated. This > prevents a race between more CPUs eventually updating the same hierarchy > of h_load_next return pointers. Is there an actual problem observed?