Re: Small miscellaneous fixes

Em qua., 16 de nov. de 2022 às 03:59, Michael Paquier <michael(at)paquier(dot)xyz>
escreveu:

> On Tue, Oct 04, 2022 at 08:23:16AM -0300, Ranier Vilela wrote:
> > Both are correct, I missed the pqsignal calls.
> >
> > Attached patch to change this.
>
> The change for pgbench is missing and this is only changing
> pg_test_fsync. Switching to sig_atomic_t would be fine on non-WIN32
> as these are used in signal handlers, but are we sure that this is
> fine on WIN32 for pg_test_fsync where we rely on a separate thread to
> control the timing of the alarm?
>
Well I tested here in Windows 10 64 bits with sig_atomic_t alarm_triggered
and works fine.
ctrl + c breaks the exe.

Windows 10 64bits
SSD 256GB

For curiosity, this is the test results:
5 seconds per test
O_DIRECT supported on this platform for open_datasync and open_sync.

Compare file sync methods using one 8kB write:
(in wal_sync_method preference order, except fdatasync is Linux's default)
open_datasync

ctrl + c

C:\postgres_debug\bin>pg_test_fsync
5 seconds per test
O_DIRECT supported on this platform for open_datasync and open_sync.

Compare file sync methods using one 8kB write:
(in wal_sync_method preference order, except fdatasync is Linux's default)
open_datasync

ctrl + c

C:\postgres_debug\bin>pg_test_fsync
5 seconds per test
O_DIRECT supported on this platform for open_datasync and open_sync.

Compare file sync methods using one 8kB write:
(in wal_sync_method preference order, except fdatasync is Linux's default)
open_datasync 9495,720 ops/sec 105 usecs/op
fdatasync 444,174 ops/sec 2251 usecs/op
fsync 398,487 ops/sec 2509 usecs/op
fsync_writethrough 342,018 ops/sec 2924 usecs/op
open_sync n/a

Compare file sync methods using two 8kB writes:
(in wal_sync_method preference order, except fdatasync is Linux's default)
open_datasync 4719,825 ops/sec 212 usecs/op
fdatasync 442,138 ops/sec 2262 usecs/op
fsync 401,163 ops/sec 2493 usecs/op
fsync_writethrough 397,198 ops/sec 2518 usecs/op
open_sync n/a

Compare open_sync with different write sizes:
(This is designed to compare the cost of writing 16kB in different write
open_sync sizes.)
1 * 16kB open_sync write n/a
2 * 8kB open_sync writes n/a
4 * 4kB open_sync writes n/a
8 * 2kB open_sync writes n/a
16 * 1kB open_sync writes n/a

Test if fsync on non-write file descriptor is honored:
(If the times are similar, fsync() can sync data written on a different
descriptor.)
write, fsync, close 77,808 ops/sec 12852 usecs/op
write, close, fsync 77,469 ops/sec 12908 usecs/op

Non-sync'ed 8kB writes:
write 139789,685 ops/sec 7 usecs/op

regards,
Ranier Vilela