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| author | NeilBrown <neilb@suse.de> | 2011-10-11 16:50:01 +1100 |
|---|---|---|
| committer | NeilBrown <neilb@suse.de> | 2011-10-11 16:50:01 +1100 |
| commit | 34db0cd60f8a1f4ab73d118a8be3797c20388223 (patch) | |
| tree | 45d1d629d6b9195d47d30980595686c9a3ee92f9 /drivers/md/raid1.h | |
| parent | 84fc4b56db85cb9e05326424049973a2036c9940 (diff) | |
| download | linux-34db0cd60f8a1f4ab73d118a8be3797c20388223.tar.bz2 | |
md: add proper write-congestion reporting to RAID1 and RAID10.
RAID1 and RAID10 handle write requests by queuing them for handling by
a separate thread. This is because when a write-intent-bitmap is
active we might need to update the bitmap first, so it is good to
queue a lot of writes, then do one big bitmap update for them all.
However writeback request devices to appear to be congested after a
while so it can make some guesstimate of throughput. The infinite
queue defeats that (note that RAID5 has already has a finite queue so
it doesn't suffer from this problem).
So impose a limit on the number of pending write requests. By default
it is 1024 which seems to be generally suitable. Make it configurable
via module option just in case someone finds a regression.
Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'drivers/md/raid1.h')
| -rw-r--r-- | drivers/md/raid1.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h index 5b16d09817df..c732b6cce935 100644 --- a/drivers/md/raid1.h +++ b/drivers/md/raid1.h @@ -46,6 +46,7 @@ struct r1conf { /* queue pending writes to be submitted on unplug */ struct bio_list pending_bio_list; + int pending_count; /* for use when syncing mirrors: * We don't allow both normal IO and resync/recovery IO at |