Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756050AbWK3GEc (ORCPT ); Thu, 30 Nov 2006 01:04:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756383AbWK3GEc (ORCPT ); Thu, 30 Nov 2006 01:04:32 -0500 Received: from mail.gmx.net ([213.165.64.20]:10425 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S1756050AbWK3GEb (ORCPT ); Thu, 30 Nov 2006 01:04:31 -0500 X-Authenticated: #14349625 Subject: Re: [patch 1/4] - Potential performance bottleneck for Linxu TCP From: Mike Galbraith To: Andrew Morton Cc: David Miller , wenji@fnal.gov, netdev@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20061129170835.72bd40b3.akpm@osdl.org> References: <20061129.165311.45739865.davem@davemloft.net> <20061129170835.72bd40b3.akpm@osdl.org> Content-Type: text/plain Date: Thu, 30 Nov 2006 07:04:25 +0100 Message-Id: <1164866665.5913.33.camel@Homer.simpson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.6.0 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1400 Lines: 37 On Wed, 2006-11-29 at 17:08 -0800, Andrew Morton wrote: > + if (p->backlog_flag == 0) { > + if (!TASK_INTERACTIVE(p) || expired_starving(rq)) { > + enqueue_task(p, rq->expired); > + if (p->static_prio < rq->best_expired_prio) > + rq->best_expired_prio = p->static_prio; > + } else > + enqueue_task(p, rq->active); > + } else { > + if (expired_starving(rq)) { > + enqueue_task(p,rq->expired); > + if (p->static_prio < rq->best_expired_prio) > + rq->best_expired_prio = p->static_prio; > + } else { > + if (!TASK_INTERACTIVE(p)) > + p->extrarun_flag = 1; > + enqueue_task(p,rq->active); > + } > + } (oh my, doing that to the scheduler upsets my tummy, but that aside...) I don't see how that can really solve anything. "Interactive" tasks starting to use cpu heftily can still preempt and keep the special cased cpu hog off the cpu for ages. It also only takes one task in the expired array to trigger the forced array switch with a fully loaded cpu, and once any task hits the expired array, a stream of wakeups can prevent the switch from completing for as long as you can keep wakeups happening. -Mike - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/