Em sex., 27 de mai. de 2022 às 18:08, Andres Freund <and...@anarazel.de> escreveu:
> Hi, > > On 2022-05-27 03:30:46 +0200, Tomas Vondra wrote: > > On 5/27/22 02:11, Ranier Vilela wrote: > > > ./pgbench -M prepared -c $conns -j $conns -T 60 -S -n -U postgres > > > > > > pgbench (15beta1) > > > transaction type: <builtin: select only> > > > scaling factor: 1 > > > query mode: prepared > > > number of clients: 100 > > > number of threads: 100 > > > maximum number of tries: 1 > > > duration: 60 s > > > > > > conns tps head tps patched > > > > > > 1 17126.326108 17792.414234 > > > 10 82068.123383 82468.334836 > > > 50 73808.731404 74678.839428 > > > 80 73290.191713 73116.553986 > > > 90 67558.483043 68384.906949 > > > 100 65960.982801 66997.793777 > > > 200 62216.011998 62870.243385 > > > 300 62924.225658 62796.157548 > > > 400 62278.099704 63129.555135 > > > 500 63257.930870 62188.825044 > > > 600 61479.890611 61517.913967 > > > 700 61139.354053 61327.898847 > > > 800 60833.663791 61517.913967 > > > 900 61305.129642 61248.336593 > > > 1000 60990.918719 61041.670996 > > > > > > > These results look much saner, but IMHO it also does not show any clear > > benefit of the patch. Or are you still claiming there is a benefit? > > They don't look all that sane to me - isn't that way lower than one would > expect? Yes, quite disappointing. Restricting both client and server to the same four cores, a > thermically challenged older laptop I have around I get 150k tps at both 10 > and 100 clients. > And you can share the benchmark details? Hardware, postgres and pgbench, please? > > Either way, I'd not expect to see any GetSnapshotData() scalability > effects to > show up on an "Intel® Core™ i5-8250U CPU Quad Core" - there's just not > enough > concurrency. > This means that our customers will not see any connections scalability with PG15, using the simplest hardware? > The correct pieces of these changes seem very unlikely to affect > GetSnapshotData() performance meaningfully. > > To improve something like GetSnapshotData() you first have to come up with > a > workload that shows it being a meaningful part of a profile. Unless it is, > performance differences are going to just be due to various forms of noise. > Actually in the profiles I got with perf, GetSnapShotData() didn't show up. regards, Ranier Vilela
