On 5/25/22 11:07, Ranier Vilela wrote:
> Em qua., 25 de mai. de 2022 às 00:46, Andres Freund <and...@anarazel.de
> <mailto:and...@anarazel.de>> escreveu:
>
> Hi Andres, thank you for taking a look.
>
>
> On 2022-05-24 12:28:20 -0300, Ranier Vilela wrote:
> > Linux Ubuntu 64 bits (gcc 9.4)
> > ./pgbench -M prepared -c $conns -j $conns -S -n -U postgres
> >
> > conns tps head tps patched
> > 1 2918.004085 3190.810466
> > 10 12262.415696 17199.862401
> > 50 13656.724571 18278.194114
> > 80 14338.202348 17955.336101
> > 90 16597.510373 18269.660184
> > 100 17706.775793 18349.650150
> > 200 16877.067441 17881.250615
> > 300 16942.260775 17181.441752
> > 400 16794.514911 17124.533892
> > 500 16598.502151 17181.244953
> > 600 16717.935001 16961.130742
> > 700 16651.204834 16959.172005
> > 800 16467.546583 16834.591719
> > 900 16588.241149 16693.902459
> > 1000 16564.985265 16936.952195
>
> 17-18k tps is pretty low for pgbench -S. For a shared_buffers
> resident run, I
> can get 40k in a single connection in an optimized build. If you're
> testing a
> workload >> shared_buffers, GetSnapshotData() isn't the bottleneck. And
> testing an assert build isn't a meaningful exercise either, unless
> you have
> way way higher gains (i.e. stuff like turning O(n^2) into O(n)).
>
> Thanks for sharing these hits.
> Yes, their 17-18k tps are disappointing.
>
>
> What pgbench scale is this and are you using an optimized build?
>
> Yes this optimized build.
> CFLAGS='-Wall -Wmissing-prototypes -Wpointer-arith
> -Wdeclaration-after-statement -Werror=vla -Wendif-labels
> -Wmissing-format-attribute -Wimplicit-fallthrough=3 -Wcast-function-type
> -Wformat-security -fno-strict-aliasing -fwrapv
> -fexcess-precision=standard -Wno-format-truncation
> -Wno-stringop-truncation -O2'
> from config.log
>
That can still be assert-enabled build. We need to see configure flags.
> pgbench was initialized with:
> pgbench -i -p 5432 -d postgres
>
> pgbench -M prepared -c 100 -j 100 -S -n -U postgres
You're not specifying duration/number of transactions to execute. So
it's using just 10 transactions per client, which is bound to give you
bogus results due to not having anything in relcache etc. Use -T 60 or
something like that.
> pgbench (15beta1)
> transaction type: <builtin: select only>
> scaling factor: 1
> query mode: prepared
> number of clients: 100
> number of threads: 100
>
> The shared_buffers is default:
> shared_buffers = 128MB
>
> Intel® Core™ i5-8250U CPU Quad Core
> RAM 8GB
> SSD 256 GB
>
Well, quick results on my laptop (i7-9750H, so not that different from
what you have):
1 = 18908.080126
2 = 32943.953182
3 = 42316.079028
4 = 46700.087645
So something is likely wrong in your setup.
regards
--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
