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authorMikulas Patocka <mpatocka@redhat.com>2014-01-13 19:13:05 -0500
committerMike Snitzer <snitzer@redhat.com>2014-01-14 23:23:03 -0500
commit55b082e614e219fb5199a6f93e648ed35d3c96d5 (patch)
treea2707e62bdd914e9651e78cde6cb55a5f0b88d7f /drivers/md/dm-bufio.h
parent55494bf2947dccdf2d98b62374fea7365dfead84 (diff)
downloadop-kernel-dev-55b082e614e219fb5199a6f93e648ed35d3c96d5.zip
op-kernel-dev-55b082e614e219fb5199a6f93e648ed35d3c96d5.tar.gz
dm snapshot: use dm-bufio prefetch
This patch modifies dm-snapshot so that it prefetches the buffers when loading the exceptions. The number of buffers read ahead is specified in the DM_PREFETCH_CHUNKS macro. The current value for DM_PREFETCH_CHUNKS (12) was found to provide the best performance on a single 15k SCSI spindle. In the future we may modify this default or make it configurable. Also, introduce the function dm_bufio_set_minimum_buffers to setup bufio's number of internal buffers before freeing happens. dm-bufio may hold more buffers if enough memory is available. There is no guarantee that the specified number of buffers will be available - if you need a guarantee, use the argument reserved_buffers for dm_bufio_client_create. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-bufio.h')
-rw-r--r--drivers/md/dm-bufio.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/md/dm-bufio.h b/drivers/md/dm-bufio.h
index 3dac376..c096779 100644
--- a/drivers/md/dm-bufio.h
+++ b/drivers/md/dm-bufio.h
@@ -115,6 +115,11 @@ void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block);
*/
void dm_bufio_forget(struct dm_bufio_client *c, sector_t block);
+/*
+ * Set the minimum number of buffers before cleanup happens.
+ */
+void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n);
+
unsigned dm_bufio_get_block_size(struct dm_bufio_client *c);
sector_t dm_bufio_get_device_size(struct dm_bufio_client *c);
sector_t dm_bufio_get_block_number(struct dm_buffer *b);
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