| commit | df5d2e9089c7d5b8c46f767e4278610ea3e815b9 | |
| author | Mikulas Patocka <mpatocka@redhat.com> | |
| Fri, 1 Mar 2013 22:45:49 +0000 (1 22:45 +0000) | ||
| committer | Alasdair G Kergon <agk@redhat.com> | |
| Fri, 1 Mar 2013 22:45:49 +0000 (1 22:45 +0000) | ||
| tree | 5285aa8b0c794da419133a209437b32a11aa8a8d | treesnapshot (tar.gz zip) |
| parent | a26062416ef8add48f16fbadded2b5f6fb84d024 | commitdiff |
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>
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>