From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id CA8B26B0012 for ; Thu, 26 May 2011 07:44:13 -0400 (EDT) Received: by bwz17 with SMTP id 17so511214bwz.14 for ; Thu, 26 May 2011 04:44:11 -0700 (PDT) Date: Thu, 26 May 2011 13:44:06 +0200 From: Tejun Heo Subject: Re: [RFC][PATCH v3 7/10] workqueue: add WQ_IDLEPRI Message-ID: <20110526114406.GG9715@htj.dyndns.org> References: <20110526141047.dc828124.kamezawa.hiroyu@jp.fujitsu.com> <20110526143024.7f66e797.kamezawa.hiroyu@jp.fujitsu.com> <20110526093808.GE9715@htj.dyndns.org> <20110526193018.12b3ddea.kamezawa.hiroyu@jp.fujitsu.com> <20110526195019.8af6d882.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110526195019.8af6d882.kamezawa.hiroyu@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org List-ID: To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , Ying Han , "nishimura@mxp.nes.nec.co.jp" , "balbir@linux.vnet.ibm.com" Hello, On Thu, May 26, 2011 at 07:50:19PM +0900, KAMEZAWA Hiroyuki wrote: > On Thu, 26 May 2011 19:30:18 +0900 > KAMEZAWA Hiroyuki wrote: > > In the next version, I'll try some like.. > > == > > process_one_work(...) { > > ..... > > spin_unlock_irq(&gcwq->lock); > > ..... > > if (cwq->wq->flags & WQ_IDLEPRI) { > > set_scheduler(...SCHED_IDLE...) > > cond_resched(); > > scheduler_switched = true; > > } > > f(work) > > if (scheduler_switched) > > set_scheduler(...SCHED_OTHER...) > > spin_lock_irq(&gcwq->lock); > > } > > == > > Patch size will be much smaller. (Should I do this in memcg's code ??) > > > > BTW, my concern is that if f(work) is enough short,effect of SCHED_IDLE will never > be found because SCHED_OTHER -> SCHED_IDLE -> SCHED_OTHER switch is very fast. > Changed "weight" of CFQ never affects the next calculation of vruntime..of the > thread and the work will show the same behavior with SCHED_OTHER. > > I'm sorry if I misunderstand CFQ and setscheduler(). Hmm... I'm not too familiar there either but, * If prio is lowered (you're gonna lower it too, right?), prio_changed_fair() is called which in turn does resched_task() as necessary. * More importantly, for short work items, it's likely to not matter at all. If you can determine beforehand that it's not gonna take very long time, queueing on system_wq would be more efficient. Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org