Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262520AbVCIWvz (ORCPT ); Wed, 9 Mar 2005 17:51:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262519AbVCIWtc (ORCPT ); Wed, 9 Mar 2005 17:49:32 -0500 Received: from fmr21.intel.com ([143.183.121.13]:1999 "EHLO scsfmr001.sc.intel.com") by vger.kernel.org with ESMTP id S262187AbVCIWSV (ORCPT ); Wed, 9 Mar 2005 17:18:21 -0500 Message-Id: <200503092218.j29MICg26503@unix-os.sc.intel.com> From: "Chen, Kenneth W" To: "'Andrew Morton'" Cc: , Subject: RE: Direct io on block device has performance regression on 2.6.x kernel Date: Wed, 9 Mar 2005 14:18:12 -0800 X-Mailer: Microsoft Office Outlook, Build 11.0.6353 Thread-Index: AcUk41c0T8r0hQONT7+Vrd+cGQzRygADEiRgAAE9mMA= In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 982 Lines: 26 Chen, Kenneth W wrote on Wednesday, March 09, 2005 1:59 PM > > Did you generate a kernel profile? > > Top 40 kernel hot functions, percentage is normalized to kernel utilization. > > _spin_unlock_irqrestore 23.54% > _spin_unlock_irq 19.27% > .... > > Profile with spin lock inlined, so that it is easier to see functions > that has the lock contention, again top 40 hot functions: Just to clarify here, these data need to be taken at grain of salt. A high count in _spin_unlock_* functions do not automatically points to lock contention. It's one of the blind spot syndrome with timer based profile on ia64. There are some lock contentions in 2.6 kernel that we are staring at. Please do not misinterpret the number here. - Ken - 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/