On 1/12/2021 11:45 PM, David Sterba wrote:
On Tue, Jan 12, 2021 at 11:36:14PM +0800, kernel test robot wrote:Greeting, FYI, we noticed a -18.3% regression of fio.write_iops due to commit: commit: e076ab2a2ca70a0270232067cd49f76cd92efe64 ("btrfs: shrink delalloc pages instead of full inodes") https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master in testcase: fio-basic on test machine: 192 threads Intel(R) Xeon(R) CPU @ 2.20GHz with 192G memory with following parameters: disk: 1SSD fs: btrfs runtime: 300s nr_task: 8 rw: randwrite bs: 4k ioengine: sync test_size: 256gThough I do a similar test (emulating bit torrent workload), it's a bit extreme as it's 4k synchronous on a huge file. It always takes a lot of time but could point out some concurrency issues namely on faster devices. There are 8 threads possibly competing for the same inode lock or other locks related to it. The mentioned commit fixed another perf regression on a much more common workload (untgrring files), so at this point drop in this fio workload is inevitable.
Do you have a plan to fix it? Thanks.
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-- Zhengjun Xing
