From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 61A786B0089 for ; Tue, 23 Nov 2010 01:02:31 -0500 (EST) Date: Mon, 22 Nov 2010 21:57:46 -0800 From: Andrew Morton Subject: Re: [RFC] mlock: release mmap_sem every 256 faulted pages Message-Id: <20101122215746.e847742d.akpm@linux-foundation.org> In-Reply-To: <20101123050052.GA24039@google.com> References: <20101123050052.GA24039@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Michel Lespinasse Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hugh Dickins , KOSAKI Motohiro , Nick Piggin , Rik van Riel List-ID: On Mon, 22 Nov 2010 21:00:52 -0800 Michel Lespinasse wrote: > Hi, > > I'd like to sollicit comments on this proposal: > > Currently mlock() holds mmap_sem in exclusive mode while the pages get > faulted in. In the case of a large mlock, this can potentially take a > very long time. A more compelling description of why this problem needs addressing would help things along. > + /* > + * Limit batch size to 256 pages in order to reduce > + * mmap_sem hold time. > + */ > + nfault = nstart + 256 * PAGE_SIZE; It would be nicer if there was an rwsem API to ask if anyone is currently blocked in down_read() or down_write(). That wouldn't be too hard to do. It wouldn't detect people polling down_read_trylock() or down_write_trylock() though. -- 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 policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org