On Tue, Jul 11, 2023 at 12:34 AM Andres Freund <and...@anarazel.de> wrote: > > Hi, > > On 2023-07-03 11:55:13 +0900, Masahiko Sawada wrote: > > While testing PG16, I observed that in PG16 there is a big performance > > degradation in concurrent COPY into a single relation with 2 - 16 > > clients in my environment. I've attached a test script that measures > > the execution time of COPYing 5GB data in total to the single relation > > while changing the number of concurrent insertions, in PG16 and PG15. > > Here are the results on my environment (EC2 instance, RHEL 8.6, 128 > > vCPUs, 512GB RAM): > > Gah, RHEL with its frankenkernels, the bane of my existance. > > FWIW, I had extensively tested this with XFS, just with a newer kernel. Have > you tested this on RHEL9 as well by any chance?
I've tested this on RHEL9 (m5.24xlarge; 96vCPUs, 384GB RAM), and it seems to be reproducible on RHEL9 too. $ uname -rms Linux 5.14.0-284.11.1.el9_2.x86_64 x86_64 $ cat /etc/redhat-release Red Hat Enterprise Linux release 9.2 (Plow) PG15: nclients = 1, execution time = 22.193 PG15: nclients = 2, execution time = 12.430 PG15: nclients = 4, execution time = 8.677 PG15: nclients = 8, execution time = 6.144 PG15: nclients = 16, execution time = 5.938 PG15: nclients = 32, execution time = 5.775 PG15: nclients = 64, execution time = 5.928 PG15: nclients = 128, execution time = 6.346 PG15: nclients = 256, execution time = 6.641 PG16: nclients = 1, execution time = 24.601 PG16: nclients = 2, execution time = 27.845 PG16: nclients = 4, execution time = 40.575 PG16: nclients = 8, execution time = 24.379 PG16: nclients = 16, execution time = 15.835 PG16: nclients = 32, execution time = 8.370 PG16: nclients = 64, execution time = 4.042 PG16: nclients = 128, execution time = 2.956 PG16: nclients = 256, execution time = 2.591 Tests with test.c program: $ rm -f test.data; time ./test test.data 0 total 200000 fallocate 0 filewrite 200000 real 0m0.709s user 0m0.057s sys 0m0.649s $ rm -f test.data; time ./test test.data 1 total 200000 fallocate 200000 filewrite 0 real 0m0.853s user 0m0.058s sys 0m0.791s $ rm -f test.data; time ./test test.data 2 total 200000 fallocate 100000 filewrite 100000 real 2m10.002s user 0m0.366s sys 0m6.649s Regards, -- Masahiko Sawada Amazon Web Services: https://aws.amazon.com
