Some architectures have pages larger than 4k and committing a full page causes needless overhead.
Fix this by writing a single block when committing the superblock. Writes smaller than 4k are slow on most SSDs (because the SSD performs read-modify-write internally), so make sure that we write at least 4k. Signed-off-by: Mikulas Patocka <[email protected]> Index: linux-2.6/drivers/md/dm-writecache.c =================================================================== --- linux-2.6.orig/drivers/md/dm-writecache.c +++ linux-2.6/drivers/md/dm-writecache.c @@ -532,7 +532,7 @@ static void ssd_commit_superblock(struct region.bdev = wc->ssd_dev->bdev; region.sector = 0; - region.count = PAGE_SIZE >> SECTOR_SHIFT; + region.count = max(4096U, wc->block_size) >> SECTOR_SHIFT; if (unlikely(region.sector + region.count > wc->metadata_sectors)) region.count = wc->metadata_sectors - region.sector; -- dm-devel mailing list [email protected] https://listman.redhat.com/mailman/listinfo/dm-devel
