From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753453AbcKPN7i (ORCPT ); Wed, 16 Nov 2016 08:59:38 -0500 Received: from smtprelay0047.hostedemail.com ([216.40.44.47]:51055 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751277AbcKPN7f (ORCPT ); Wed, 16 Nov 2016 08:59:35 -0500 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::::::,RULES_HIT:41:355:379:541:543:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1542:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:2691:3138:3139:3140:3141:3142:3354:3622:3865:3866:3867:3870:3871:3872:3873:3874:4321:4605:5007:6119:6261:7875:7903:10004:10400:10848:10967:11026:11232:11658:11914:12043:12296:12438:12555:12740:12760:12986:13302:13439:14096:14097:14180:14181:14659:14721:21080:21324:21433:21451:30006:30034:30054:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:2,LUA_SUMMARY:none X-HE-Tag: rain33_705fc9589f25a X-Filterd-Recvd-Size: 3121 Date: Wed, 16 Nov 2016 08:59:30 -0500 From: Steven Rostedt To: Byungchul Park Cc: paulmck@linux.vnet.ibm.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] rcu: Avoid unnecessary contention of rcu node lock Message-ID: <20161116085930.36924d81@gandalf.local.home> In-Reply-To: <20161116044931.GD2279@X58A-UD3R> References: <1478681833-23397-1-git-send-email-byungchul.park@lge.com> <20161116044931.GD2279@X58A-UD3R> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Importance: high X-Priority: 1 (Highest) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 16 Nov 2016 13:49:31 +0900 Byungchul Park wrote: > On Wed, Nov 09, 2016 at 05:57:13PM +0900, Byungchul Park wrote: > > It's unnecessary to try to print stacks of blocked tasks in the case > > that ndetected == 0. Furthermore, calling rcu_print_detail_task_stall() > > causes to acquire rnp locks as many times as the number of leaf nodes > > plus one for root node. It's unnecessary at all in the case. > > Hello, > > I have two questions. Could you answer them? > > 1. What do you think about this patch? > 2. Is there a tree where patches about rcu are pulled into, before > being pulled into mainline tree? > For example, tip tree in case of scheduler patches. I believe Paul sends to the tip tree too. > > It would be appriciated if you answer them. > > Thank you in advance, > Byungchul > > > > > Signed-off-by: Byungchul Park > > --- > > kernel/rcu/tree.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > index 287f468..ab2f743 100644 > > --- a/kernel/rcu/tree.c > > +++ b/kernel/rcu/tree.c > > @@ -1374,6 +1374,9 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum) > > (long)rsp->gpnum, (long)rsp->completed, totqlen); > > if (ndetected) { > > rcu_dump_cpu_stacks(rsp); > > + > > + /* Complain about tasks blocking the grace period. */ > > + rcu_print_detail_task_stall(rsp); > > } else { > > if (READ_ONCE(rsp->gpnum) != gpnum || > > READ_ONCE(rsp->completed) == gpnum) { > > @@ -1390,9 +1393,6 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum) > > } What about showing it in else statement of the above if as well? sched_show_task(current); rcu_print_detail_task_stall(rsp); -- Steve > > } > > > > - /* Complain about tasks blocking the grace period. */ > > - rcu_print_detail_task_stall(rsp); > > - > > rcu_check_gp_kthread_starvation(rsp); > > > > panic_on_rcu_stall(); > > -- > > 1.9.1