On Thu, Aug 08, 2019 at 08:08:17AM +1000, Dave Chinner wrote: > On Wed, Aug 07, 2019 at 04:03:16PM +0100, Mel Gorman wrote: > > > > inode cache shrinker is not being called when large batches of pages > > > > are being reclaimed. In roughly the same time period that it takes > > > > to fill memory with 50% pages and 50% slab caches, memory reclaim > > > > reduces the page cache down to just dirty pages and slab caches fill > > > > the entirity of memory. > > > > > > > > At the point where the page cache is reduced to just the dirty > > > > pages, there is a clear change in write IO patterns. Up to this > > > > point it has been running at a steady 1500 write IOPS for ~200MB/s > > > > of write throughtput (data, journal and metadata). > > > > As observed by iostat -x or something else? Sum of r/s and w/s would > > PCP + live pmcharts. Same as I've done for 15+ years :) > > I could look at iostat, but it's much easier to watch graphs run > and then be able to double click on any point and get the actual > value. > > I've attached a screen shot of the test machine overview while the > vanilla kernel runs the fsmark test (cpu, iops, IO bandwidth, XFS > create/remove/lookup ops, context switch rate and memory usage) at a > 1 second sample rate. You can see the IO patterns change, the > context switch rate go nuts and the CPU usage pattern change when > the page cache hits empty. And now attached. :) Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
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