Hi! > 30 апр. 2018 г., в 23:15, Andres Freund <and...@anarazel.de> написал(а): > On 2018-04-30 15:39:08 +0500, Andrey Borodin wrote: >> I suspect that performance benefits can be not that big or even >> marginal, if we do not extend comprehensive eviction strategy with >> bgwriter fixes and O_DIRECT. > > If so, then the improvements aren't real. Bgwriter doesn't matter for > read-only workloads. O_DIRECT doesn't matter much if shared_buffers are > 60+% of OS memory. And even disregarding that, you can just compute > cache hit ratios to see whether things are improving. Even considering simply changing eviction strategy - it is not just about hit ratio. It is also about eviction complexity less than O(N).
But I think you are right. If we compare performance effect of half-measures in the real system, probably it is more accurate than comparing isolated algorithms in a sand box. Best regards, Andrey Borodin.
