On Sun, 2026-04-26 at 21:44 +0100, Matthew Wilcox wrote: > On Sun, Apr 26, 2026 at 07:56:08AM -0400, Jeff Layton wrote: > > Mixed-mode noisy neighbor (dontcache writer + buffered readers): > > baseline patched change > > writer (MB/s) 1297.6 1471.1 +13.4% > > readers avg (MB/s) 855.0 462.4 -45.9% > > hm. This wasn't what I thought of when I thought of "noisy neighbour". > I'd have process A doing DONTCACHE writes to file A and process B doing > normal buffered writes to file B.
Originally, I was benchmarking this via nfsd and only later did I add the suite for local benchmarks. With nfsd, setting the iomode affects all reads or writes. So initially, I had it testing them with both reads and writes set to the same setting, but then later I decided to play with different modes for reads and writes. The best performing one was buffered reads + dontcache writes. It's possible a mix of different modes will be better on a local fs. I can't easily do a benchmark like you're suggesting with nfsd, but it should be possible on a local benchmark. I'll see what I can come up with. Thanks, -- Jeff Layton <[email protected]>
