From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263227AbUEOTu0 (ORCPT ); Sat, 15 May 2004 15:50:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264717AbUEOTu0 (ORCPT ); Sat, 15 May 2004 15:50:26 -0400 Received: from phoenix.infradead.org ([213.86.99.234]:38412 "EHLO phoenix.infradead.org") by vger.kernel.org with ESMTP id S263227AbUEOTuZ (ORCPT ); Sat, 15 May 2004 15:50:25 -0400 Date: Sat, 15 May 2004 20:50:22 +0100 From: Christoph Hellwig To: Jens Axboe Cc: Christoph Hellwig , torvalds@osdl.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] slabify iocontext + request_queue Message-ID: <20040515205022.A4788@infradead.org> Mail-Followup-To: Christoph Hellwig , Jens Axboe , torvalds@osdl.org, linux-kernel@vger.kernel.org References: <20040515190735.A4189@infradead.org> <20040515173004.GA962@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20040515173004.GA962@suse.de>; from axboe@suse.de on Sat, May 15, 2004 at 07:30:04PM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 15, 2004 at 07:30:04PM +0200, Jens Axboe wrote: > > While I agree on the io_context part, slabifying request_queue is a space > > waste on most machines out there. The averange desktop has less than a > > handfull of these, and even for smaller servers it doesn't exactly look > > like a gain. > > See the thread last week on queue congestion threshold calculations, > there were some numbers in there. Maybe my math is completely off, but with slab you'd need a page at least, the kmem_cache_t and maybe a kmem_bufctl_t So for the usual two or three queue desktops we went from 1024 or 1536 to 4096 + N. Cutoff point is at aproximately 9 queues which I think most machines running linux won't reach. Anyway, not that this is really important, I think we just need to question all this silent bloating a little..