From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751340AbZL1TX3 (ORCPT ); Mon, 28 Dec 2009 14:23:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751195AbZL1TX2 (ORCPT ); Mon, 28 Dec 2009 14:23:28 -0500 Received: from one.firstfloor.org ([213.235.205.2]:55314 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751127AbZL1TX2 (ORCPT ); Mon, 28 Dec 2009 14:23:28 -0500 Date: Mon, 28 Dec 2009 20:23:25 +0100 From: Andi Kleen To: Pekka Enberg Cc: Andi Kleen , Nitin Gupta , Hugh Dickins , KAMEZAWA Hiroyuki , Andrew Morton , linux-kernel Subject: Re: [PATCH 1/2] [mmotm] Add notifiers for various swap events Message-ID: <20091228192325.GG4994@basil.fritz.box> References: <1261963200-7136-1-git-send-email-ngupta@vflare.org> <87eimf87m5.fsf@basil.nowhere.org> <4B38D0CF.9000403@vflare.org> <20091228172903.GF4994@basil.fritz.box> <4B38FC42.7000204@cs.helsinki.fi> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B38FC42.7000204@cs.helsinki.fi> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>>> The first question to ask is if compressed swap is worth >>>> it. Do you have benchmark numbers showing it to be an improvement? >>>> Are there cases where it is slower than uncompressed swap? >>>> >>> http://code.google.com/p/compcache/wiki/Performance >> >> That should be included in the changelog of the patches. > > Which patches? The driver is already in staging and there's a pointer to > the home page in How can it be in staging if there are no hooks for it yet? >>> ramzswap is an optional module. >> >> I have some doubts on the wisdom of making swap algorithms modular. >> Better compile them in. Then you don't need messy notifiers either. > > What's so messy about them? The whole point of having the notifiers is to > avoid CONFIG_RAMZSWAP in core kernel code... They make the code much harder to read and follow. When you try to follow the code flow and you find a notifier it's always a complicated operation to figure out what code will end up being called. Sometimes they are needed, but they have a high cost in maintainability. -Andi -- ak@linux.intel.com -- Speaking for myself only.