From patchwork Wed Aug 19 11:25:54 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 31640 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by bilbo.ozlabs.org (Postfix) with ESMTP id 56266B708B for ; Wed, 19 Aug 2009 21:26:14 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751694AbZHSLZy (ORCPT ); Wed, 19 Aug 2009 07:25:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751710AbZHSLZy (ORCPT ); Wed, 19 Aug 2009 07:25:54 -0400 Received: from brick.kernel.dk ([93.163.65.50]:32860 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751526AbZHSLZx (ORCPT ); Wed, 19 Aug 2009 07:25:53 -0400 Received: by kernel.dk (Postfix, from userid 1000) id 0808737A0C2; Wed, 19 Aug 2009 13:25:55 +0200 (CEST) Date: Wed, 19 Aug 2009 13:25:54 +0200 From: Jens Axboe To: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Cc: jeff@garzik.org, htejun@gmail.com Subject: [PATCH] libata: use single threaded work queue Message-ID: <20090819112554.GY12579@kernel.dk> MIME-Version: 1.0 Content-Disposition: inline Sender: linux-ide-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ide@vger.kernel.org Hi, On boxes with lots of CPUs, we have so many kernel threads it's not funny. The basic problem is that create_workqueue() creates a per-cpu thread, where we could easily get by with a single thread for a lot of cases. One such case appears to be ata_wq. You want at most one per pio drive, not one per CPU. I'd suggest just dropping it to a single threaded wq. Signed-off-by: Jens Axboe diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index 072ba5e..0d78628 100644 --- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -6580,7 +6580,7 @@ static int __init ata_init(void) { ata_parse_force_param(); - ata_wq = create_workqueue("ata"); + ata_wq = create_singlethread_workqueue("ata"); if (!ata_wq) goto free_force_tbl;