From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 20 Mar 2001 17:33:49 +0100 From: Andi Kleen Subject: Re: 3rd version of R/W mmap_sem patch available Message-ID: <20010320173349.A4839@fred.local> References: <3AB77311.77EB7D60@uow.edu.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: ; from torvalds@transmeta.com on Tue, Mar 20, 2001 at 05:08:36PM +0100 Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: Andrew Morton , linux-mm@kvack.org List-ID: 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 ? -Andi -- 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/