On Thu, 14 Sep 2023 09:44:42 +1000, Dave Chinner <david@xxxxxxxxxxxxx> wrote: > On Wed, Sep 13, 2023 at 11:41:15AM +0800, alexjlzheng@xxxxxxxxx wrote: > > On Mon, 11 Sep 2023 07:49:51 +1000, Dave Chinner <david@xxxxxxxxxxxxx> wrote: > > > On Sat, Sep 09, 2023 at 03:17:51PM +0800, alexjlzheng@xxxxxxxxx wrote: > > > > From: Jinliang Zheng <alexjlzheng@xxxxxxxxxxx> > > > > > > > > Historically, when generic percpu counters were introduced in xfs for > > > > free block counters by commit 0d485ada404b ("xfs: use generic percpu > > > > counters for free block counter"), the counters used a custom batch > > > > size. In xfs_mod_freecounter(), originally named xfs_mod_fdblocks(), > > > > this patch attempted to serialize the program using a smaller batch size > > > > as parameter to the addition function as the counter approaches 0. > > > > > > > > Commit 8c1903d3081a ("xfs: inode and free block counters need to use > > > > __percpu_counter_compare") pointed out the error in commit 0d485ada404b > > > > ("xfs: use generic percpu counters for free block counter") mentioned > > > > above and said that "Because the counters use a custom batch size, the > > > > comparison functions need to be aware of that batch size otherwise the > > > > comparison does not work correctly". Then percpu_counter_compare() was > > > > replaced with __percpu_counter_compare() with parameter > > > > XFS_FDBLOCKS_BATCH. > > > > > > > > After commit 8c1903d3081a ("xfs: inode and free block counters need to > > > > use __percpu_counter_compare"), the existence of the batch variable is > > > > no longer necessary, so this patch is proposed to simplify the code by > > > > removing it. > > > > > > Hmmmm. Fiddling with percpu counter batch thresholds can expose > > > unexpected corner case behaviours. What testing have you done on > > > this change? > > > > Hi, Dave, > > > > Thank you for your reply. > > > > I have tested the patch using _filebench_ and _fio_. > > What about all the ENOSPC and shutdown tests in fstests? Sorry for the late reply. I tested this patch using xfstests last week, and all enospc and shutdown related tests passed. > > If you haven't exercised ENOSPC conditions in your testing, then you > haven't actually tested whether the new code can accurately and > correctly detect ENOSPC conditions.... > > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx Best regards, Jinliang Zheng.