Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757588Ab1EXAya (ORCPT ); Mon, 23 May 2011 20:54:30 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:40909 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752871Ab1EXAy1 (ORCPT ); Mon, 23 May 2011 20:54:27 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Message-ID: <4DDB0199.6030805@jp.fujitsu.com> Date: Tue, 24 May 2011 09:53:45 +0900 From: Hidetoshi Seto User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; ja; rv:1.9.2.17) Gecko/20110414 Thunderbird/3.1.10 MIME-Version: 1.0 To: Xiao Guangrong CC: Paul Turner , linux-kernel@vger.kernel.org, Peter Zijlstra , Bharata B Rao , Dhaval Giani , Balbir Singh , Vaidyanathan Srinivasan , Srivatsa Vaddagiri , Kamalesh Babulal , Ingo Molnar , Pavel Emelyanov Subject: Re: Test for CFS Bandwidth Control V6 References: <20110323030326.789836913@google.com> <4DD5CE05.3030500@cn.fujitsu.com> In-Reply-To: <4DD5CE05.3030500@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3499 Lines: 139 Hi Paul and Xiao, Please check/test a fix at the foot of this mail. (2011/05/20 11:12), Xiao Guangrong wrote: > Hi Paul, > > I'm so sorry for sending this mail in the new thread, since i didn't > receive your V6 patchset from LKML. > > It seams the patchset can not be applied, since it's conflict between > patch 3 and patch 5: > > ========Quote======== (snip) > ========End quote======== Maybe I've fixed it by hand, or git-am is so wonderful. I believe Paul will do it right for next time. > > I downloaded the patchset from Internet, i missed the newer version? > > I have done some test after fixed the conflict by handle, below test can cause > box crash: > > ========Quote　cpu_hotlpug.sh ======== (snip) > ======== End quote　cpu_hotlpug.sh ======== > > Sorry to disturb you if the bug is know. > > Thanks! Thank you for reporting it, Xiao! I confirmed that running your test cause hung-up on my box. And after some investigation, I found that this is an infinite loop in migrate_task() due to miscalculation of rq->nr_running; when a task is queued to throttled entity the nr_running is incremented at the queuing and also the unthrottling. I made a fix for this bug and it seems works well for me. Could you try this patch and give us your feedback, Xiao? Thanks, H.Seto --- kernel/sched_fair.c | 28 +++++++++++++--------------- 1 files changed, 13 insertions(+), 15 deletions(-) diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 3936393..544072f 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1537,7 +1537,7 @@ static void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) walk_tg_tree_from(cfs_rq->tg, tg_unthrottle_down, tg_nop, (void *)&udd); - if (!cfs_rq->load.weight) + if (!cfs_rq->h_nr_running) return; task_delta = cfs_rq->h_nr_running; @@ -1843,10 +1843,9 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) cfs_rq->h_nr_running++; /* end evaluation on throttled cfs_rq */ - if (cfs_rq_throttled(cfs_rq)) { - se = NULL; - break; - } + if (cfs_rq_throttled(cfs_rq)) + goto done; + flags = ENQUEUE_WAKEUP; } @@ -1855,14 +1854,14 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) cfs_rq->h_nr_running++; if (cfs_rq_throttled(cfs_rq)) - break; + goto done; update_cfs_load(cfs_rq, 0); update_cfs_shares(cfs_rq); } - if (!se) - inc_nr_running(rq); + inc_nr_running(rq); +done: hrtick_update(rq); } @@ -1885,10 +1884,9 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) cfs_rq->h_nr_running--; /* end evaluation on throttled cfs_rq */ - if (cfs_rq_throttled(cfs_rq)) { - se = NULL; - break; - } + if (cfs_rq_throttled(cfs_rq)) + goto done; + /* Don't dequeue parent if it has other entities besides us */ if (cfs_rq->load.weight) { /* Avoid double update below. */ @@ -1910,14 +1908,14 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) cfs_rq->h_nr_running--; if (cfs_rq_throttled(cfs_rq)) - break; + goto done; update_cfs_load(cfs_rq, 0); update_cfs_shares(cfs_rq); } - if (!se) - dec_nr_running(rq); + dec_nr_running(rq); +done: hrtick_update(rq); } -- 1.7.4.4 -- 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/