Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756950Ab2EXCMR (ORCPT ); Wed, 23 May 2012 22:12:17 -0400 Received: from out5-smtp.messagingengine.com ([66.111.4.29]:60736 "EHLO out5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751993Ab2EXCMQ (ORCPT ); Wed, 23 May 2012 22:12:16 -0400 X-Sasl-enc: ljdyX9+exMQkdGRasggBzQ3FeubzbHJjNTAsElQQBp+o 1337825534 Date: Wed, 23 May 2012 19:12:08 -0700 From: Greg KH To: Joe Perches Cc: Alan Stern , Kay Sievers , Kernel development list , Jason Baron , Thomas Gleixner Subject: Re: Excessive latency for dev_dbg? Message-ID: <20120524021208.GA12557@kroah.com> References: <1337805903.1747.0.camel@joe2Laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1337805903.1747.0.camel@joe2Laptop> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 980 Lines: 27 On Wed, May 23, 2012 at 01:45:03PM -0700, Joe Perches wrote: > cc'ing Kay. > > On Wed, 2012-05-23 at 16:37 -0400, Alan Stern wrote: > > I just tried doing some testing of 3.4. Sequences of literally > > adjacent dev_dbg() calls -- with local interrupts disabled -- show up > > in the log buffer spaced at time intervals between 1 and 4 > > milliseconds! > > > > This is with CONFIG_DYNAMIC_DEBUG not enabled, and CONFIG_PRINTK_TIME, > > CONFIG_PREEMPT, CONFIG_HIGH_RES_TIMERS, and CONFIG_HPET_TIMER all set > > to y. > > > > What's going on here? Did printk suddenly slow down a lot? Or has the > > timer code gone crazy? Joe, why ask Kay? He didn't touch this code until 3.5-rc1, and Alan is testing 3.4. confused, greg k-h -- 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/