From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 5 Jul 2002 17:31:29 -0700 (PDT) From: Linus Torvalds Subject: Re: vm lock contention reduction In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Rik van Riel Cc: Andrew Morton , William Lee Irwin III , Andrea Arcangeli , "linux-mm@kvack.org" List-ID: On Fri, 5 Jul 2002, Rik van Riel wrote: > > But it is, mmap() and anonymous memory don't trigger writeback. I don't think we can fix that, without going back to the approach of marking any writable memory as read-only and counting it at page-fault time. Wasn't it you who did that test-patch originally? From what I remember, it had basically zero downside for normal UNIX applications (shared memory that is written to is so rare that it doesn't end up on the radar), but was quite expensive for the DB kind of shmem usage where shared writable memory is the major component.. There might be some way to avoid the page fault badness (the large page stuff will do this automatically, for example), which might make the "let's keep track of dirty mappings explicitly" approach acceptable again. Linus -- 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/