From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752836Ab1IWJlV (ORCPT ); Fri, 23 Sep 2011 05:41:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:18969 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752669Ab1IWJlS (ORCPT ); Fri, 23 Sep 2011 05:41:18 -0400 From: "Daniel P. Berrange" To: Neil Brown Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, "Daniel P. Berrange" Subject: [PATCH] md: don't delay reboot by 1 second if no MD devices exist Date: Fri, 23 Sep 2011 10:40:45 +0100 Message-Id: <1316770845-18171-1-git-send-email-berrange@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Daniel P. Berrange" The md_notify_reboot() method includes a call to mdelay(1000), to deal with "exotic SCSI devices" which are too volatile on reboot. The delay is unconditional. Even if the machine does not have any block devices, let alone MD devices, the kernel shutdown sequence is slowed down. 1 second does not matter much with physical hardware, but with certain virtualization use cases any wasted time in the bootup & shutdown sequence counts for alot. * drivers/md/md.c: md_notify_reboot() - only impose a delay if there was at least one MD device to be stopped during reboot Signed-off-by: Daniel P. Berrange --- drivers/md/md.c | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 5404b22..ef7ad8d 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8059,12 +8059,13 @@ static int md_notify_reboot(struct notifier_block *this, { struct list_head *tmp; mddev_t *mddev; + int need_delay = 0; if ((code == SYS_DOWN) || (code == SYS_HALT) || (code == SYS_POWER_OFF)) { printk(KERN_INFO "md: stopping all md devices.\n"); - for_each_mddev(mddev, tmp) + for_each_mddev(mddev, tmp) { if (mddev_trylock(mddev)) { /* Force a switch to readonly even array * appears to still be in use. Hence @@ -8073,13 +8074,16 @@ static int md_notify_reboot(struct notifier_block *this, md_set_readonly(mddev, 100); mddev_unlock(mddev); } + need_delay = 1; + } /* * certain more exotic SCSI devices are known to be * volatile wrt too early system reboots. While the * right place to handle this issue is the given * driver, we do want to have a safe RAID driver ... */ - mdelay(1000*1); + if (need_delay) + mdelay(1000*1); } return NOTIFY_DONE; } -- 1.7.6.2