From owner-svn-src-all@FreeBSD.ORG Sat Mar 8 00:35:07 2014 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 85E41F49; Sat, 8 Mar 2014 00:35:07 +0000 (UTC) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 735A5217; Sat, 8 Mar 2014 00:35:07 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.8/8.14.8) with ESMTP id s280Z7F9036150; Sat, 8 Mar 2014 00:35:07 GMT (envelope-from jeff@svn.freebsd.org) Received: (from jeff@localhost) by svn.freebsd.org (8.14.8/8.14.8/Submit) id s280Z7xF036149; Sat, 8 Mar 2014 00:35:07 GMT (envelope-from jeff@svn.freebsd.org) Message-Id: <201403080035.s280Z7xF036149@svn.freebsd.org> From: Jeff Roberson Date: Sat, 8 Mar 2014 00:35:07 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r262917 - head/sys/kern X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 08 Mar 2014 00:35:07 -0000 Author: jeff Date: Sat Mar 8 00:35:06 2014 New Revision: 262917 URL: http://svnweb.freebsd.org/changeset/base/262917 Log: - Make runq_steal_from more aggressive. Previously it would examine only a single priority queue. If that queue had a thread or threads which could not be migrated we would fail to steal load. This could cause starvation in situations where cores are idle. Submitted by: Doug Kilpatrick Tested by: pho Reviewed by: mav Sponsored by: EMC / Isilon Storage Division Modified: head/sys/kern/sched_ule.c Modified: head/sys/kern/sched_ule.c ============================================================================== --- head/sys/kern/sched_ule.c Sat Mar 8 00:14:40 2014 (r262916) +++ head/sys/kern/sched_ule.c Sat Mar 8 00:35:06 2014 (r262917) @@ -1057,32 +1057,27 @@ runq_steal_from(struct runq *rq, int cpu struct rqhead *rqh; struct thread *td, *first; int bit; - int pri; int i; rqb = &rq->rq_status; bit = start & (RQB_BPW -1); - pri = 0; first = NULL; again: for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { if (rqb->rqb_bits[i] == 0) continue; - if (bit != 0) { - for (pri = bit; pri < RQB_BPW; pri++) - if (rqb->rqb_bits[i] & (1ul << pri)) - break; - if (pri >= RQB_BPW) + if (bit == 0) + bit = RQB_FFS(rqb->rqb_bits[i]); + for (; bit < RQB_BPW; bit++) { + if ((rqb->rqb_bits[i] & (1ul << bit)) == 0) continue; - } else - pri = RQB_FFS(rqb->rqb_bits[i]); - pri += (i << RQB_L2BPW); - rqh = &rq->rq_queues[pri]; - TAILQ_FOREACH(td, rqh, td_runq) { - if (first && THREAD_CAN_MIGRATE(td) && - THREAD_CAN_SCHED(td, cpu)) - return (td); - first = td; + rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)]; + TAILQ_FOREACH(td, rqh, td_runq) { + if (first && THREAD_CAN_MIGRATE(td) && + THREAD_CAN_SCHED(td, cpu)) + return (td); + first = td; + } } } if (start != 0) {