From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 25 Aug 2001 22:57:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 25 Aug 2001 22:57:36 -0400 Received: from islay.mach.uni-karlsruhe.de ([129.13.162.92]:56754 "EHLO mailout.plan9.de") by vger.kernel.org with ESMTP id ; Sat, 25 Aug 2001 22:57:32 -0400 Date: Sun, 26 Aug 2001 04:57:46 +0200 From: To: Rik van Riel Cc: Alan Cox , Daniel Phillips , Roger Larsson , linux-kernel@vger.kernel.org Subject: Re: [resent PATCH] Re: very slow parallel read performance Message-ID: <20010826045746.H29129@cerebro.laendle> Mail-Followup-To: Rik van Riel , Alan Cox , Daniel Phillips , Roger Larsson , linux-kernel@vger.kernel.org In-Reply-To: <20010826013442.C29129@cerebro.laendle> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Operating-System: Linux version 2.4.8-ac8 (root@cerebro) (gcc version 3.0.1) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 25, 2001 at 11:02:25PM -0300, Rik van Riel wrote: > This is because the readahead windows are too large so the > kernel ends up evicting data before its needed and has to > re-read the data. > > Also see http://linux-mm.org/wiki/moin.cgi/StreamingIo > in the Linux-MM wiki. O_STREAMING is an interesting idea (I talked with stefan traby about the problem and we came to a similar conclusion - fadvise instead of madvise, and per-file characteristics as opposed to blockdevices or global settings). Anyway, so far it really looks as if this is the case - there is some limit (around 700 conns) where the available memory doesn't suffice for read-ahead. > This problem should be relatively easy to fix for 2.4. Nice ;) -- -----==- | ----==-- _ | ---==---(_)__ __ ____ __ Marc Lehmann +-- --==---/ / _ \/ // /\ \/ / pcg@goof.com |e| -=====/_/_//_/\_,_/ /_/\_\ XX11-RIPE --+ The choice of a GNU generation | |