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| author | Mikulas Patocka <mpatocka@redhat.com> | 2013-03-01 23:45:49 +0100 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2013-03-01 23:45:49 +0100 |
| commit | df5d2e9089c7d5b8c46f767e4278610ea3e815b9 (patch) | |
| tree | 5285aa8b0c794da419133a209437b32a11aa8a8d /drivers/md/dm-thin.c | |
| parent | dm ioctl: allow message to return data (diff) | |
| download | linux-df5d2e9089c7d5b8c46f767e4278610ea3e815b9.tar.xz linux-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-thin.c')
| -rw-r--r-- | drivers/md/dm-thin.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index 303e11da7c2a..35d9d0396cc2 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -26,6 +26,9 @@ #define PRISON_CELLS 1024 #define COMMIT_PERIOD HZ +DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle, + "A percentage of time allocated for copy on write"); + /* * The block size of the device holding pool data must be * between 64KB and 1GB. @@ -1642,7 +1645,7 @@ static struct pool *pool_create(struct mapped_device *pool_md, goto bad_prison; } - pool->copier = dm_kcopyd_client_create(); + pool->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle); if (IS_ERR(pool->copier)) { r = PTR_ERR(pool->copier); *error = "Error creating pool's kcopyd client"; |