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| author | Mikulas Patocka <mpatocka@redhat.com> | 2013-03-01 22:45:49 +0000 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2013-03-01 22:45:49 +0000 |
| commit | df5d2e9089c7d5b8c46f767e4278610ea3e815b9 (patch) | |
| tree | 5285aa8b0c794da419133a209437b32a11aa8a8d /drivers/md/dm-snap.c | |
| parent | a26062416ef8add48f16fbadded2b5f6fb84d024 (diff) | |
| download | lwn-df5d2e9089c7d5b8c46f767e4278610ea3e815b9.tar.gz lwn-df5d2e9089c7d5b8c46f767e4278610ea3e815b9.zip | |
dm kcopyd: introduce configurable throttling
This patch allows the administrator to reduce the rate at which kcopyd
issues I/O.
Each module that uses kcopyd acquires a throttle parameter that can be
set in /sys/module/*/parameters.
We maintain a history of kcopyd usage by each module in the variables
io_period and total_period in struct dm_kcopyd_throttle. The actual
kcopyd activity is calculated as a percentage of time equal to
"(100 * io_period / total_period)". This is compared with the user-defined
throttle percentage threshold and if it is exceeded, we sleep.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-snap.c')
| -rw-r--r-- | drivers/md/dm-snap.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index 58c2b5881377..c0e07026a8d1 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -124,6 +124,9 @@ struct dm_snapshot { #define RUNNING_MERGE 0 #define SHUTDOWN_MERGE 1 +DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle, + "A percentage of time allocated for copy on write"); + struct dm_dev *dm_snap_origin(struct dm_snapshot *s) { return s->origin; @@ -1108,7 +1111,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) goto bad_hash_tables; } - s->kcopyd_client = dm_kcopyd_client_create(); + s->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle); if (IS_ERR(s->kcopyd_client)) { r = PTR_ERR(s->kcopyd_client); ti->error = "Could not create kcopyd client"; |