From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fernando Serboncini Subject: RAID5 resync blocking on 2.6.0-test11 Date: Thu, 11 Dec 2003 22:25:57 -0200 Sender: linux-raid-owner@vger.kernel.org Message-ID: <3FD90B15.8050905@campogeral.com.br> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi, I sent this e-mail to the LKML yesterday, that's when I found the linux-raid list. ;) So hi, LinuxRaid I've just installed a software-RAID 5 on my Alpha (miata) Workstation 500au with Kernel 2.6.0-test11. The RAID is made of 4 Western Digital 250Gb HDs on a promise-ata-133tx2. The initial raidstart and mke2fs worked fine. After the initial sync, a clean boot and a new raidstart, the /proc/mdstat reported that the drive was at "resync" (/var/log/messages says that "raid array is not clean"). The problem is, the resync was blocking the /dev/md0. So, when I did a 'mount /dev/md0', it blocked until the resync was done (and it was a looong time for a nearly 1TB RAID). Looking through driver/md code I've realized that md_do_sync() was the real devil. After a few diffs with 2.4.23 code I've realized that at the speed limiter part of the function, the old "current->nice = " lines were deleted. After a few more search (and looking through LXR) at /fs/jffs2/background.c and /net/bluetooth/bnep/core.c I've realized that some people have changed "current->nice =" statements to "set_user_nice(current,...)" ones. Done that. The RAID worked just fine (still resyncing at boot, not fully tested yet) but don't block mounts anymore (btw, mount returns a lot faster than with 2.4.23). Since I'm no kernel (nor RAID) expert (first post here, btw), just wandering if I did something really stupid or not. Also, is this an Alpha-only issue? Or a 2.6.0 issue? Anyway, here follows the patch for what I've done. thanks for the attention. Fernando Serboncini --- linux-2.6.0-test11/drivers/md/md.c 2003-11-26 18:43:29.000000000 -0200 +++ linux/drivers/md/md.c 2003-12-10 23:29:33.000000000 -0200 @@ -3290,6 +3290,8 @@ currspeed = (j-mddev->resync_mark_cnt)/2/((jiffies-mddev->resync_mark)/HZ +1) +1; if (currspeed > sysctl_speed_limit_min) { + set_user_nice(current,19); + if ((currspeed > sysctl_speed_limit_max) || !is_mddev_idle(mddev)) { current->state = TASK_INTERRUPTIBLE; @@ -3297,6 +3299,8 @@ goto repeat; } } + else + set_user_nice(current,-20); } printk(KERN_INFO "md: md%d: sync done.\n",mdidx(mddev)); /*