Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757142Ab2EXOwh (ORCPT ); Thu, 24 May 2012 10:52:37 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:54211 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754055Ab2EXOwg (ORCPT ); Thu, 24 May 2012 10:52:36 -0400 Date: Thu, 24 May 2012 10:52:35 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Lin Ming cc: Jens Axboe , Jeff Moyer , , , Subject: Re: [RFC v2 PATCH 2/4] block: add queue runtime pm callbacks In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 887 Lines: 26 On Thu, 24 May 2012, Lin Ming wrote: > > When tested the patches, I found that kjournald and flusher thread > > frequently resume the disk. > > Just found that it's because "printk". > > When disk is suspended, it prints out some message, for example, > > [ 670.597103] sd 0:0:0:0: [sda] Synchronizing SCSI cache > [ 670.597827] sd 0:0:0:0: [sda] Stopping disk > > Then syslogd is waken up to write the log. > So disk is resumed right after suspended. :-) Very amusing! So if you change those two messages in sd_suspend (and maybe also the message in sd_resume) from KERN_NOTICE to KERN_DEBUG, things ought to improve. Alan Stern -- 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/