From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx139.postini.com [74.125.245.139]) by kanga.kvack.org (Postfix) with SMTP id D36E56B004D for ; Thu, 3 May 2012 15:31:31 -0400 (EDT) Message-ID: <1336073474.6509.2.camel@twins> Subject: Re: [PATCH 1/1] mlock: split the shmlock_user_lock spinlock into per user_struct spinlock From: Peter Zijlstra Date: Thu, 03 May 2012 21:31:14 +0200 In-Reply-To: <1336066477-3964-1-git-send-email-rajman.mekaco@gmail.com> References: <1336066477-3964-1-git-send-email-rajman.mekaco@gmail.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: rajman mekaco Cc: Ingo Molnar , Paul Gortmaker , Andrew Morton , KOSAKI Motohiro , Minchan Kim , Christoph Lameter , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Thu, 2012-05-03 at 23:04 +0530, rajman mekaco wrote: > The user_shm_lock and user_shm_unlock functions use a single global > spinlock for protecting the user->locked_shm. Are you very sure its only protecting user state? This changelog doesn't convince me you've gone through everything and found it good. > This is an overhead for multiple CPUs calling this code even if they > are having different user_struct. >=20 > Remove the global shmlock_user_lock and introduce and use a new > spinlock inside of the user_struct structure.=20 While I don't immediately see anything wrong with it, I doubt its useful. What workload run with enough users that this makes a difference one way or another? -- 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