On Wed, Mar 20, 2019 at 08:47:32AM -0700, Ted Carpenter wrote: > I'm testing performance of a clustered NFS server using a 4.15 client. > My test setup involves running IOZone to write a 30GB file to the > server over NFSv3. The issue is that we occasionally see bad > performance, especially when unstable writes are enabled on the > server. Which server, and how do you enable unstable writes? > Based on observing the network traffic, we've seen the write I/O size > during good runs stay around 1MB (which is how we've mounted) but in > the bad runs we see often see dips in write size (down to even 4KB or > 8KB) towards the end of the test. > > I'm trying to understand why we see the dip in I/O size from the NFS > client as it seems to be related to the decrease in performance. Any > ideas what could cause it? Also, any suggestions on where I should > look to start learning about the way the Linux NFS client and page > cache handle unstable writes internally? I'm not sure what to recommend. We might also need some more details about the performance results you're seeing. --b.
