On Tue, Jul 21, 2020 at 9:33 PM Thomas Munro <thomas.mu...@gmail.com> wrote: > > On Wed, Jul 22, 2020 at 3:57 PM Amit Kapila <amit.kapil...@gmail.com> wrote: > > Yeah, that is true but every time before the test the same amount of > > data should be present in shared buffers (or OS cache) if any which > > will help in getting consistent results. However, it is fine to > > reboot the machine as well if that is a convenient way. > > We really should have an extension (pg_prewarm?) that knows how to > kick stuff out PostgreSQL's shared buffers and the page cache > (POSIX_FADV_DONTNEED). > > +1. Clearing the OS page cache on FreeBSD is non-trivial during testing. You can't do this on FreeBSD: sync; echo 3 > /proc/sys/vm/drop_caches
Also, it would be nice to evict only those pages from the OS page cache that are Postgres pages instead of having to drop everything. Regards, Soumyadeep (VMware)
