From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Moyer Subject: Re: SSD slowdown with 3.3.X? Date: Fri, 20 Apr 2012 11:23:25 -0400 Message-ID: References: <4F8F7533.6020300@gmail.com> <4F8F82EC.1060708@teksavvy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx1.redhat.com ([209.132.183.28]:36987 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932197Ab2DTPX2 (ORCPT ); Fri, 20 Apr 2012 11:23:28 -0400 In-Reply-To: <4F8F82EC.1060708@teksavvy.com> (Mark Lord's message of "Wed, 18 Apr 2012 23:13:48 -0400") Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Lord Cc: Joe Ceklosky , linux-ide@vger.kernel.org Mark Lord writes: > On 12-04-18 10:15 PM, Joe Ceklosky wrote: >> All, >> >> Has anyone reported slowness using SSD's on kernel 3.3.X compiled >> as 32-bit PAE with 16 Gigs of memory (I know I need to update to 64-bit >> already, will do with Fedora 17)? >> >> I am see terrible r/w to an SSD using 3.3.2. When I boot the same machine >> and SSD back in 3.2.15 all is fine. > > > Double check which IO-scheduler the kernel is choosing. > For SSDs, it is normally "noop", but I noticed "cfq" > being chosen instead for some reason. The default I/O scheduler is the default I/O scheduler. Drivers may override this (some high-end PCIe SSD drivers do this, and I think s390 block drivers do as well), but in general the default is left alone. Cheers, Jeff