From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <42BFC10E.50204@yahoo.com.au> Date: Mon, 27 Jun 2005 19:04:14 +1000 From: Nick Piggin MIME-Version: 1.0 Subject: Re: [rfc] lockless pagecache References: <42BF9CD1.2030102@yahoo.com.au> <20050627004624.53f0415e.akpm@osdl.org> <42BFB287.5060104@yahoo.com.au> <42BFBF5B.7080301@cisco.com> In-Reply-To: <42BFBF5B.7080301@cisco.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Lincoln Dale Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Lincoln Dale wrote: > Nick Piggin wrote: > [..] > >> However I think for Oracle and others that use shared memory like >> this, they are probably not doing linear access, so that would be a >> net loss. I'm not completely sure (I don't have access to real loads >> at the moment), but I would have thought those guys would have looked >> into fault ahead if it were a possibility. > > > i thought those guys used O_DIRECT - in which case, wouldn't the page > cache not be used? > Well I think they do use O_DIRECT for their IO, but they need to use the Linux pagecache for their shared memory - that shared memory being the basis for their page cache. I think. Whatever the setup I believe they have issues with the tree_lock, which is why it was changed to an rwlock. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com -- 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/ . Don't email: aart@kvack.org