Hi, > > On May 31, 2022, at 6:34 AM, Wang Yugui <wangyugui@xxxxxxxxxxxx> wrote: > > > > When many(>NFSD_FILE_LRU_THRESHOLD) files are kept as OPEN, such as > > xfstests generic/531, nfsd proceses are in CPU high-load state, > > and nfsd_file_gc(nfsd filecache garbage collector) waste many CPU times. > > Over the past few days, I've been able to reproduce a lot of bad > behavior with generic/531. My test client has 12 physical CPU > cores, and my lab network is 56Gb InfiniBand. > > Unfortunately this patch doesn't really begin to address it. For > example, with this patch applied, CPU idle is in single digits > on the NFS server that exports the test's scratch device, and > that server can still get into a soft lock-up. IMO that is > because this change works around the underlying problem but > makes no attempt to root-cause or address that issue. > > I agree that the NFS server's behavior needs attention, but I'm > not inclined to apply this particular patch as it is. Yes. this patch is just particular for xfstests generic/531. In xfstests generic/531, when many(>500K ) files are kept as OPEN, a file delete will cause LRU walk( CPU soft look-up) too. big LRU data is still fast to add, but very slow to remove some random one? Best Regards Wang Yugui (wangyugui@xxxxxxxxxxxx) 2022/05/31
