From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from renko.ucs.ed.ac.uk (renko.ucs.ed.ac.uk [129.215.13.3]) by kvack.org (8.8.7/8.8.7) with ESMTP id LAA26593 for ; Thu, 25 Jun 1998 11:52:08 -0400 Date: Thu, 25 Jun 1998 12:35:02 +0100 Message-Id: <199806251135.MAA00851@dax.dcs.ed.ac.uk> From: "Stephen C. Tweedie" MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Subject: Re: Thread implementations... In-Reply-To: References: Sender: owner-linux-mm@kvack.org To: "Eric W. Biederman" Cc: Dean Gaudet , Richard Gooch , linux-kernel@vger.rutgers.edu, linux-mm@kvack.org List-ID: Hi, On 24 Jun 1998 23:56:28 -0500, ebiederm+eric@npwt.net (Eric W. Biederman) said: > mmap, madvise(SEQUENTIAL),write > is easy to implement. The mmap layer already does readahead, all we > do is tell it not to be so conservative. Swap readhead is also now possible. However, madvise(SEQUENTIAL) needs to do much more than this; it needs to aggressively track what region of the vma is being actively used, and to unmap those areas no longer in use. (They can remain in cache until the memory is needed for something else, of course.) The madvise is only going to be important if the whole file / vma does not fit into memory, so having advice that a piece of memory not recently accessed is unlikely to be accessed again until the next sequential pass is going to be very valuable. It will prevent us from having to swap out more useful stuff. --Stephen