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This adds some new cache functions to qcow2 which can be used for caching refcount blocks and L2 tables. When used with cache=writethrough they work like the old caching code which is spread all over qcow2, so for this case we have merely a cleanup. The interesting case is with writeback caching (this includes cache=none) where data isn't written to disk immediately but only kept in cache initially. This leads to some form of metadata write batching which avoids the current "write to refcount block, flush, write to L2 table" pattern for each single request when a lot of cluster allocations happen. Instead, cache entries are only written out if its required to maintain the right order. In the pure cluster allocation case this means that all metadata updates for requests are done in memory initially and on sync, first the refcount blocks are written to disk, then fsync, then L2 tables. This improves performance of scenarios with lots of cluster allocations noticably (e.g. installation or after taking a snapshot). Signed-off-by: Kevin Wolf <kwolf@redhat.com> |
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| .. | ||
| blkdebug.c | ||
| blkverify.c | ||
| bochs.c | ||
| cloop.c | ||
| cow.c | ||
| curl.c | ||
| dmg.c | ||
| nbd.c | ||
| parallels.c | ||
| qcow.c | ||
| qcow2-cache.c | ||
| qcow2-cluster.c | ||
| qcow2-refcount.c | ||
| qcow2-snapshot.c | ||
| qcow2.c | ||
| qcow2.h | ||
| qed-check.c | ||
| qed-cluster.c | ||
| qed-gencb.c | ||
| qed-l2-cache.c | ||
| qed-table.c | ||
| qed.c | ||
| qed.h | ||
| raw-posix-aio.h | ||
| raw-posix.c | ||
| raw-win32.c | ||
| raw.c | ||
| rbd.c | ||
| rbd_types.h | ||
| sheepdog.c | ||
| vdi.c | ||
| vmdk.c | ||
| vpc.c | ||
| vvfat.c | ||