On Tue, May 13, 2025 at 11:37:45AM -0700, Salvatore Dipietro wrote: > On Thu, 1 May 2025 at 14:50, Nathan Bossart <nathandboss...@gmail.com> wrote: >> So... >> >> * The ISB does seem to have a positive effect without commit 3d0b4b1 >> applied. >> >> * With commit 3d0b4b1 applied, removing the ISB seems to have a positive >> effect at high concurrencies. This is especially pronounced in the >> pgbench test. >> >> * With commit 3d0b4b1 applied, removing the ISB doesn't change much at >> lower concurrencies, and there might even be a small regression. >> >> * At mostly lower concurrencies, commit 3d0b4b1 actually seems to regress >> some test_shm_mq tests. Removing the ISB instruction appears to help in >> some cases, but not all. > > Based on your findings Nathan, what is the best way to proceed for this > change? > Do we need more validation for it? If yes, which kind?
Well, I am confused because your recent message [0] indicated that you saw improvement without the non-locking initial test in TAS_SPIN, which seems to contradict my findings [1]. Could you retry your tests on v18devel? It might also be useful to repeat the tests on a variety of hardware to ensure it's a win across the board. [0] https://postgr.es/m/CAGnuAhXNQXCcS1nCeD6E0Dyfi4Ms-b0sjcm79Y9iMi5WxUqM4g%40mail.gmail.com [1] https://postgr.es/m/aBPsrFbjnrqp3_8S%40nathan -- nathan
