| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Dimitrios Apostolou <jimis(at)gmx(dot)net> |
| Cc: | Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>, Nathan Bossart <nathandbossart(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, pgsql-hackers(at)lists(dot)postgresql(dot)org |
| Subject: | Re: [PATCH v4] parallel pg_restore: avoid disk seeks when jumping short distance forward |
| Date: | 2025-10-20 22:23:27 |
| Message-ID: | 382528.1760999007@sss.pgh.pa.us |
| Views: | Whole Thread | Raw Message | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Dimitrios Apostolou <jimis(at)gmx(dot)net> writes:
> Thanks for the extensive testing! Did you see the same syscall pattern in strace output, as I did?
Yes, I did look at that, and it's the same as you saw:
HEAD repeats
read(4k)
lseek(~128k forward)
which is to be expected if we have to read data block headers
that are ~128K apart; while patched repeats
read(4k)
read(~128k)
which is a bit odd in itself, why isn't it merging the reads better?
> I was using an HDD,
Ah. Your original message mentioned NVMe so I was assuming you
were also looking at solid-state drives. I can imagine that
seeking is more painful on HDDs ...
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Mihail Nikalayeu | 2025-10-20 22:26:00 | Re: isolation tester limitation in case of multiple injection points in a single command |
| Previous Message | Masahiko Sawada | 2025-10-20 22:18:50 | Re: Logical Replication of sequences |