From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933404AbbFVN2f (ORCPT ); Mon, 22 Jun 2015 09:28:35 -0400 Received: from casper.infradead.org ([85.118.1.10]:48749 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754011AbbFVN23 (ORCPT ); Mon, 22 Jun 2015 09:28:29 -0400 Date: Mon, 22 Jun 2015 15:28:21 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: Dave Hansen , Andi Kleen , dave.hansen@linux.intel.com, akpm@linux-foundation.org, jack@suse.cz, viro@zeniv.linux.org.uk, eparis@redhat.com, john@johnmccutchan.com, rlove@rlove.org, tim.c.chen@linux.intel.com, linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH] fs: optimize inotify/fsnotify code for unwatched files Message-ID: <20150622132821.GB12596@twins.programming.kicks-ass.net> References: <20150619215025.4F689817@viggo.jf.intel.com> <20150619233306.GT25760@tassilo.jf.intel.com> <5584B62F.5080506@sr71.net> <20150620022135.GF3913@linux.vnet.ibm.com> <5585AAA0.1030305@sr71.net> <20150621013058.GH3913@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150621013058.GH3913@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jun 20, 2015 at 06:30:58PM -0700, Paul E. McKenney wrote: > Well, it is not hard to have an SRCU-like thing that doesn't have > read-side memory barriers, given that older versions of SRCU didn't > have them. However, the price is increased latency for the analog to > synchronize_srcu(). I am guessing that this would not be a problem > for notification-group destruction, which is presumably rare. I don't think it ever makes sense to optimize for a global state. So screw sync_srcu() and make the srcu_read_lock() thing go fast. If you need fast global state you're doing it wrong. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in Please read the FAQ at http://www.tux.org/lkml/