kernel/linux.git/include/linux/dm-kcopyd.h, branch v6.19.11

dm: change "unsigned" to "unsigned int"

2023-02-14T19:23:06+00:00

Signed-off-by: Heinz Mauelshagen Signed-off-by: Mike Snitzer

dm: add missing SPDX-License-Indentifiers

2023-02-14T19:23:06+00:00

'GPL-2.0-only' is used instead of 'GPL-2.0' because SPDX has deprecated its use. Suggested-by: John Wiele Signed-off-by: Heinz Mauelshagen Signed-off-by: Mike Snitzer

dm writecache: have ssd writeback wait if the kcopyd workqueue is busy

2021-06-15T19:42:03+00:00

Make dm-writecache wait if the kcopyd workqueue is busy (as will happen if waiting for page allocation or inside submit_bio). This change improves performance of "mkfs.ext2" by approximately 20% on one testbed. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer

dm kcopyd: return void from dm_kcopyd_copy()

2018-07-31T21:33:21+00:00

dm_kcopyd_copy() only ever returns 0 so there is no need for callers to account for possible failure. Same goes for dm_kcopyd_zero(). Signed-off-by: Mike Snitzer

dm kcopyd: add sequential write feature

2017-06-19T15:03:51+00:00

When copyying blocks to host-managed zoned block devices, writes must be sequential. However, dm_kcopyd_copy() does not guarantee this as writes are issued in the completion order of reads, and reads may complete out of order despite being issued sequentially. Fix this by introducing the DM_KCOPYD_WRITE_SEQ feature flag. This can be specified when calling dm_kcopyd_copy() and should be set automatically if one of the destinations is a host-managed zoned block device. For a split job, the master job maintains the write position at which writes must be issued. This is checked with the pop() function which is modified to not return any write I/O sub job that is not at the correct write position. When DM_KCOPYD_WRITE_SEQ is specified for a job, errors cannot be ignored and the flag DM_KCOPYD_IGNORE_ERROR is ignored, even if specified by the user. Signed-off-by: Damien Le Moal Reviewed-by: Hannes Reinecke Reviewed-by: Bart Van Assche Signed-off-by: Mike Snitzer

dm kcopyd: introduce configurable throttling

2013-03-01T22:45:49+00:00

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 Signed-off-by: Alasdair G Kergon

dm kcopyd: add dm_kcopyd_zero to zero an area

2011-10-31T20:18:58+00:00

This patch introduces dm_kcopyd_zero() to make it easy to use kcopyd to write zeros into the requested areas instead instead of copying. It is implemented by passing a NULL copying source to dm_kcopyd_copy(). The forthcoming thin provisioning target uses this. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon

dm snapshot: skip reading origin when overwriting complete chunk

2011-08-02T11:32:04+00:00

If we write a full chunk in the snapshot, skip reading the origin device because the whole chunk will be overwritten anyway. This patch changes the snapshot write logic when a full chunk is written. In this case: 1. allocate the exception 2. dispatch the bio (but don't report the bio completion to device mapper) 3. write the exception record 4. report bio completed Callbacks must be done through the kcopyd thread, because callbacks must not race with each other. So we create two new functions: dm_kcopyd_prepare_callback: allocate a job structure and prepare the callback. (This function must not be called from interrupt context.) dm_kcopyd_do_callback: submit callback. (This function may be called from interrupt context.) Performance test (on snapshots with 4k chunk size): without the patch: non-direct-io sequential write (dd): 17.7MB/s direct-io sequential write (dd): 20.9MB/s non-direct-io random write (mkfs.ext2): 0.44s with the patch: non-direct-io sequential write (dd): 26.5MB/s direct-io sequential write (dd): 33.2MB/s non-direct-io random write (mkfs.ext2): 0.27s Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon

dm kcopyd: return client directly and not through a pointer

2011-05-29T12:03:13+00:00

Return client directly from dm_kcopyd_client_create, not through a parameter, making it consistent with dm_io_client_create. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon

dm kcopyd: reserve fewer pages

2011-05-29T12:03:11+00:00

Reserve just the minimum of pages needed to process one job. Because we allocate pages from page allocator, we don't need to reserve a large number of pages. The maximum job size is SUB_JOB_SIZE and we calculate the number of reserved pages based on this. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon