On Tue, May 28, 2019 at 10:16:39AM -0700, Jeffrey Baker wrote: > On Sun, May 26, 2019 at 8:32 PM Dave Chinner <david@xxxxxxxxxxxxx> wrote: > > On Fri, May 24, 2019 at 01:34:58PM -0700, Jeffrey Baker wrote: > > > Write rates on the nvme drives are all exactly the md0 rates / 4, so > > > that seems normal. > > > > Write rates aren't that important - what do the io latencies, queue > > depths and device utilisation figures look like? > > 10s of microseconds, ~zero, and ~zero respectively. So it sounds like the devices aren't showing signs of slowness, but the filesystem and memory reclaim is sitting there twiddling it's thumbs waiting for IO to complete? Perhaps it might be worthwhile running a latency trace (e.g. with ftrace or one of the newfangled bpf tools) to find out where everything is blocking and how long they are waiting for things to occur. That might give some more insight into what resource we are waiting to be released to make progress... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
