Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759088Ab2EWUhb (ORCPT ); Wed, 23 May 2012 16:37:31 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:48641 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1758666Ab2EWUha (ORCPT ); Wed, 23 May 2012 16:37:30 -0400 Date: Wed, 23 May 2012 16:37:29 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Kernel development list cc: Jason Baron , Thomas Gleixner , Greg KH Subject: Excessive latency for dev_dbg? 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: 709 Lines: 19 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? 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/