22.04.2021 19:30, Vladimir Sementsov-Ogievskiy wrote:
Hi all!It's an alternative lock-less solution to [PATCH v4 0/3] qcow2: fix parallel rewrite and discard (rw-lock) In v6 a lot of things are rewritten. What is changed: 1. rename the feature to host_range_refcnt, move it to separate file 2. better naming for everything (I hope) 3. cover reads, not only writes 4. do "ref" in qcow2_get_host_offset(), qcow2_alloc_host_offset(), qcow2_alloc_compressed_cluster_offset(). and callers do "unref" appropriately.
About performance. With these series we do extra allocations and hash-map operations.. Still testing by ./build/qemu-img bench -c 1000000 -s 4K --image-opts driver=null-co,size=5G and ./build/qemu-img bench -c 1000000 -s 4K -w --image-opts driver=null-co,size=5G I see difference less than 1%. -- Best regards, Vladimir
