On Sat, Oct 17, 2020 at 2:11 PM Kent Overstreet <kent.overstreet@xxxxxxxxx> wrote: > > Convert generic_file_buffered_read() to get pages to read from in > batches, and then copy data to userspace from many pages at once - in > particular, we now don't touch any cachelines that might be contended > while we're in the loop to copy data to userspace. > > This is is a performance improvement on workloads that do buffered reads > with large blocksizes, and a very large performance improvement if that > file is also being accessed concurrently by different threads. > > On smaller reads (512 bytes), there's a very small performance > improvement (1%, within the margin of error). I ran this through my buffered testing, and no ill effects observed. It also provides a nice boost on the read side for a mixed read/write verification workload I have. Reviewed-by: Jens Axboe <axboe@xxxxxxxxx> -- Jens Axboe
