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[209.132.180.67]) by mx.google.com with ESMTP id s21si14176870pfi.87.2018.04.24.07.35.17; Tue, 24 Apr 2018 07:35:31 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=fail header.i=@infradead.org header.s=merlin.20170209 header.b=3jktMKz8; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757462AbeDXMwZ (ORCPT + 99 others); Tue, 24 Apr 2018 08:52:25 -0400 Received: from merlin.infradead.org ([205.233.59.134]:38376 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933222AbeDXMtA (ORCPT ); Tue, 24 Apr 2018 08:49:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=s/lXsCVYsTPBWq4Eu+NAStcC5r4d5zCHpOombnSzeZI=; b=3jktMKz8pYNmu99JjXFVGB0qW bgukG9k6TR+V5FXBD/g0TSGHJ3fvTTumz993EXi9yEkHp4wDnNCt54qc/XLoutDcCI9JqGqy/eOpZ /soPDsaptO7G3IgseoJRPZDMIwoLRTw25Tqi3xD4N0PRvZknCDq7LwENBtJ6T02YNrnfiQavGnZ+a fsR3pNsXLvjNk8cWBj4YXa0CmBfbXYe9P3oPhNYAuAPc9x1j22PgwldfaaCQTAyQYXauzkMoH2/G2 6++KjjC0R70NDOVL5ZDLpnadyenRAAIhrHSrBJ+NtOulh9Ytl+Ukd+bryjvZnx1LVVjlk5GlHpThE UNPuDdHoQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fAxNQ-0000zS-C5; Tue, 24 Apr 2018 12:48:56 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 18CA7203BFAF2; Tue, 24 Apr 2018 14:48:55 +0200 (CEST) Date: Tue, 24 Apr 2018 14:48:55 +0200 From: Peter Zijlstra To: subhra mazumdar Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, daniel.lezcano@linaro.org, steven.sistare@oracle.com, dhaval.giani@oracle.com, rohit.k.jain@oracle.com Subject: Re: [PATCH 3/3] sched: limit cpu search and rotate search window for scalability Message-ID: <20180424124855.GT4082@hirez.programming.kicks-ass.net> References: <20180424004116.28151-1-subhra.mazumdar@oracle.com> <20180424004116.28151-4-subhra.mazumdar@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180424004116.28151-4-subhra.mazumdar@oracle.com> User-Agent: Mutt/1.9.3 (2018-01-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 23, 2018 at 05:41:16PM -0700, subhra mazumdar wrote: > Lower the lower limit of idle cpu search in select_idle_cpu() and also put > an upper limit. This helps in scalability of the search by restricting the > search window. Also rotating the search window with help of next_cpu > ensures any idle cpu is eventually found in case of high load. So this patch does 2 (possibly 3) things, that's not good.