On Tue, Mar 11, 2025 at 5:00 AM Masahiko Sawada <sawada.m...@gmail.com> wrote: > > On Sun, Mar 9, 2025 at 11:28 PM Amit Kapila <amit.kapil...@gmail.com> wrote: > > > > > > Does phase 3 also use parallelism? If so, can we try to divide the > > ring buffers among workers or at least try vacuum with an increased > > number of ring buffers. This would be good to do for both the phases, > > if they both use parallelism. > > No, only phase 1 was parallelized in this test. In parallel vacuum, > since it uses (ring_buffer_size * parallel_degree) memory, more pages > are loaded during phase 1, increasing cache hits during phase 3. >
Shouldn't we ideally try with a vacuum without parallelism with ring_buffer_size * parallel_degree to make the comparison better? Also, what could be the reason for the variation in data of phase-I? Do you restart the system after each run to ensure there is nothing in the memory? If not, then shouldn't we try at least a few runs by restarting the system before each run to ensure there is nothing leftover in memory? -- With Regards, Amit Kapila.
