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From: | Vladimir Sementsov-Ogievskiy |
Subject: | Re: [PATCH v6 00/12] qcow2: fix parallel rewrite and discard (lockless) |
Date: | Mon, 26 Apr 2021 15:15:01 +0300 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 |
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
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