From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from burns.conectiva (burns.conectiva [10.0.0.4]) by postfix.conectiva.com.br (Postfix) with SMTP id E241916DC4 for ; Tue, 20 Mar 2001 16:35:51 -0300 (EST) Date: Tue, 20 Mar 2001 16:33:34 -0300 (BRST) From: Rik van Riel Subject: Re: 3rd version of R/W mmap_sem patch available In-Reply-To: <20010320173349.A4839@fred.local> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andi Kleen Cc: Linus Torvalds , Andrew Morton , linux-mm@kvack.org List-ID: On Tue, 20 Mar 2001, Andi Kleen wrote: > On Tue, Mar 20, 2001 at 05:08:36PM +0100, Linus Torvalds wrote: > > > General comment: an expensive part of a pagefault > > > is zeroing the new page. It'd be nice if we could > > > drop the page_table_lock while doing the clear_user_page() > > > and, if possible, copy_user_page() functions. Very nice. > > > > I don't think it's worth it. We should have basically zero contention on > > this lock now, and adding complexity to try to release it sounds like a > > bad idea when the only way to make contention on it is (a) kswapd (only > > when paging stuff out) and (b) multiple threads (only when taking > > concurrent page faults). > > Isn't (b) a rather common case in multi threaded applications ? Multiple threads pagefaulting on the SAME page of anonymous memory at the same time ? I can imagine multiple threads pagefaulting on the same page of some mmaped database, but on the same page of anonymous memory ?? regards, Rik -- Virtual memory is like a game you can't win; However, without VM there's truly nothing to lose... http://www.surriel.com/ http://www.conectiva.com/ http://distro.conectiva.com.br/ -- 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.eu.org/Linux-MM/