From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCHSET 8/9] prep for hotplug support Date: Thu, 27 Apr 2006 19:47:58 +0900 Message-ID: <4450A15E.4050105@gmail.com> References: <11447643813451-git-send-email-htejun@gmail.com> <44508D6A.3050200@pobox.com> <44509C98.80301@gmail.com> <44509EC7.70807@pobox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from pproxy.gmail.com ([64.233.166.177]:29086 "EHLO pproxy.gmail.com") by vger.kernel.org with ESMTP id S965088AbWD0Krh (ORCPT ); Thu, 27 Apr 2006 06:47:37 -0400 Received: by pproxy.gmail.com with SMTP id i49so2017521pye for ; Thu, 27 Apr 2006 03:47:37 -0700 (PDT) In-Reply-To: <44509EC7.70807@pobox.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jeff Garzik Cc: alan@lxorguk.ukuu.org.uk, axboe@suse.de, albertcc@tw.ibm.com, lkosewsk@gmail.com, linux-ide@vger.kernel.org Jeff Garzik wrote: > Tejun Heo wrote: >> Yeah, Forrest pointed out the same thing and I've converted hotplug_wq >> to single threaded variant, which should be enough for SCSI >> hotplugging. For ata_wq, I think it's wiser to keep it multi-threaded >> for the time being. Maybe what should be done is to allocate a single >> threaded workqueue per host_set. > > One thread per host_set would suck for any situation where that's doing > ATAPI or PIO tasks. Would love to find a good metric... Dynamic pool of worker threads maybe? > >> $BIGNUM CPU boxes tend to have $BIGNUM GB of memories, so >> multithreaded wq might not be that critical resource-wise. But, >> still, inefficient > > That's a bad assumption on modern machines. Think of a single 16-core, > 8-thread SPARC Niagara CPU, for example :) > Yeah, that one is pretty extreme. But most mainstream machines have <= 8 threads of execution and even they are equipped with GB's of memory. But, I do agree that we want something better. -- tejun