Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 31 Mar 2003 06:49:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 31 Mar 2003 06:49:38 -0500 Received: from cc78409-a.hnglo1.ov.home.nl ([212.120.97.185]:6802 "EHLO dexter.hensema.net") by vger.kernel.org with ESMTP id ; Mon, 31 Mar 2003 06:49:37 -0500 From: Erik Hensema Subject: Re: Delaying writes to disk when there's no need Date: Mon, 31 Mar 2003 12:00:57 +0000 (UTC) Message-ID: References: <20030328231248.GH5147@zaurus.ucw.cz> Reply-To: erik@hensema.net User-Agent: slrn/0.9.7.4 (Linux) To: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1206 Lines: 29 Pavel Machek (pavel@suse.cz) wrote: > Hi! > >> In all kernels I've tested writes to disk are delayed a long time even when >> there's no need to do so. >> >> A very simple test shows this: on an otherwise idle system, create a tar of >> a NFS-mounted filesystem to a local disk. The kernel starts writing out the >> data after 30 seconds, while a slow and steady stream would be much nicer >> to the system, I think. >> > > Well, doing writeback sooner when disks > are idle might be good idea; detecting > if disk is idle might not be too easy, through. Helge Hafting already pointed out that writing out the data earlier isn't desirable. The problem isn't in the waiting: the problem is in the writing. I think the current kernel tries to write too much data too fast when there's absolutely no reason to do so. It should probably gently write out small amounts of data until there is a more pressing need for memory. -- Erik Hensema - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/