Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755845AbaA1XL1 (ORCPT ); Tue, 28 Jan 2014 18:11:27 -0500 Received: from g1t0028.austin.hp.com ([15.216.28.35]:6162 "EHLO g1t0028.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754574AbaA1XLZ (ORCPT ); Tue, 28 Jan 2014 18:11:25 -0500 Message-ID: <1390950683.2807.58.camel@j-VirtualBox> Subject: Re: [PATCH v2 0/5] mutex: Mutex scalability patches From: Jason Low To: Davidlohr Bueso Cc: mingo@redhat.com, peterz@infradead.org, paulmck@linux.vnet.ibm.com, Waiman.Long@hp.com, torvalds@linux-foundation.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, riel@redhat.com, akpm@linux-foundation.org, hpa@zytor.com, andi@firstfloor.org, aswin@hp.com, scott.norton@hp.com, chegu_vinod@hp.com Date: Tue, 28 Jan 2014 15:11:23 -0800 In-Reply-To: <1390943313.11839.7.camel@buesod1.americas.hpqcorp.net> References: <1390936396-3962-1-git-send-email-jason.low2@hp.com> <1390943313.11839.7.camel@buesod1.americas.hpqcorp.net> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2014-01-28 at 13:08 -0800, Davidlohr Bueso wrote: > On Tue, 2014-01-28 at 11:13 -0800, Jason Low wrote: > > v1->v2: > > - Replace the previous patch that limits the # of times a thread can spin with > > !lock->owner with a patch that releases the mutex before holding the wait_lock > > in the __mutex_unlock_common_slowpath() function. > > - Add a patch which allows a thread to attempt 1 mutex_spin_on_owner() without > > checking need_resched() if need_resched() triggered while in the MCS queue. > > - Add a patch which disables preemption between modifying lock->owner and > > acquiring/releasing the mutex. > > > > This patchset addresses a few scalability issues with mutexes. > > > > Patch 1 has the mutex_can_spin_on_owner() funtion check for need_resched() > > before being added to MCS queue. > > > > Patches 2, 3 are to fix issues with threads spinning when > > there is no lock owner when the mutex is under high contention. > > > > Patch 4 and 5 are RFC patches. Patch 4 disables preemption between modifying > > lock->owner and locking/unlocking the mutex. Patch 5 addresses the situation > > where spinners can potentially wait a long time in the MCS queue for a chance > > to spin on mutex owner (not checking for need_resched()), yet ends up not > > getting to spin. > > > > These changes benefit the AIM7 fserver and high_systime workloads (run on disk) > > on an 8 socket, 80 core box. The table below shows the performance > > improvements with 3.13 + patches 1, 2, 3 when compared to the 3.13 baseline, > > and the performance improvements with 3.13 + all 5 patches compared to > > the 3.13 baseline. > > A lot of these changes are quite subtle. It would be good to see how > smaller systems are impacted with other workloads, not only big servers. > Since you see improvement in fserver, perhaps similar workloads could > also be of use: fio, filebench, postmark, fstress, etc. Okay, I will include the numbers I collect on smaller systems next time (even if the % difference is small). Thanks, Jason -- 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/