Messages in this thread Patch in this message | | | From | Bernd Schubert <> | Subject | Re: deadline unfairness | Date | Mon, 24 Mar 2008 17:16:05 +0100 |
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Hello Jan,
On Sunday 23 March 2008, Jan Engelhardt wrote: > On Mar 22 2008 12:25, Bernd Schubert wrote: > > some it seems the deadline scheduler is rather unfair. Below is an > > example of md-raid6 initialization of md3, md4 and md5. All three > > md-devices do share the same blockdevices (we have patched md to allow > > parallel rebuild of shared block devices, since for us the cpu is the > > bottleneck and not the block device). > > Could you share this patch? It would be really intersting for use > with fast based block devices (flash, ramdisk, and such)!
I already tried to push the patch to Neil, but I guess Neil was to busy to look at it. The patch below is for 2.6.22, but it applies to 2.6.25-git.
Signed-off-by: Bernd Schubert <bs@q-leap.de>
Index: linux-2.6.22/drivers/md/md.c =================================================================== --- linux-2.6.22.orig/drivers/md/md.c 2007-12-06 19:51:55.000000000 +0100 +++ linux-2.6.22/drivers/md/md.c 2007-12-07 12:07:47.000000000 +0100 @@ -74,6 +74,8 @@ static DEFINE_SPINLOCK(pers_lock); static void md_print_devices(void); +static DECLARE_WAIT_QUEUE_HEAD(resync_wait); + #define MD_BUG(x...) { printk("md: bug in file %s, line %d\n", __FILE__, __LINE__); md_print_devices(); } /* @@ -2843,6 +2845,34 @@ __ATTR(sync_speed_max, S_IRUGO|S_IWUSR, static ssize_t +sync_force_parallel_show(mddev_t *mddev, char *page) +{ + return sprintf(page, "%d\n", mddev->parallel_resync); +} + +static ssize_t +sync_force_parallel_store(mddev_t *mddev, const char *buf, size_t len) +{ + char *e; + unsigned long n = simple_strtoul(buf, &e, 10); + + if (!*buf || (*e && *e != '\n') || (n != 0 && n != 1)) + return -EINVAL; + + mddev->parallel_resync = n; + + if (mddev->sync_thread) { + wake_up(&resync_wait); + } + return len; +} + +/* force parallel resync, even with shared block devices */ +static struct md_sysfs_entry md_sync_force_parallel = +__ATTR(sync_force_parallel, S_IRUGO|S_IWUSR, + sync_force_parallel_show, sync_force_parallel_store); + +static ssize_t sync_speed_show(mddev_t *mddev, char *page) { unsigned long resync, dt, db; @@ -2980,6 +3010,7 @@ static struct attribute *md_redundancy_a &md_sync_min.attr, &md_sync_max.attr, &md_sync_speed.attr, + &md_sync_force_parallel.attr, &md_sync_completed.attr, &md_suspend_lo.attr, &md_suspend_hi.attr, @@ -5199,8 +5230,6 @@ void md_allow_write(mddev_t *mddev) } EXPORT_SYMBOL_GPL(md_allow_write); -static DECLARE_WAIT_QUEUE_HEAD(resync_wait); - #define SYNC_MARKS 10 #define SYNC_MARK_STEP (3*HZ) void md_do_sync(mddev_t *mddev) @@ -5264,8 +5293,9 @@ void md_do_sync(mddev_t *mddev) ITERATE_MDDEV(mddev2,tmp) { if (mddev2 == mddev) continue; - if (mddev2->curr_resync && - match_mddev_units(mddev,mddev2)) { + if (!mddev->parallel_resync + && mddev2->curr_resync + && match_mddev_units(mddev,mddev2)) { DEFINE_WAIT(wq); if (mddev < mddev2 && mddev->curr_resync == 2) { /* arbitrarily yield */ Index: linux-2.6.22/include/linux/raid/md_k.h =================================================================== --- linux-2.6.22.orig/include/linux/raid/md_k.h 2007-12-06 19:51:55.000000000 +0100 +++ linux-2.6.22/include/linux/raid/md_k.h 2007-12-06 19:52:33.000000000 +0100 @@ -170,6 +170,9 @@ struct mddev_s int sync_speed_min; int sync_speed_max; + /* resync even though the same disks are shared among md-devices */ + int parallel_resync; + int ok_start_degraded; /* recovery/resync flags * NEEDED: we might need to start a resync/recover
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