On 04/28/2017 01:34 AM, Andres Freund wrote:
On 2017-04-28 01:29:14 +0200, Tomas Vondra wrote:
I can confirm this observation. I bought the Intel 750 NVMe SSD last year,
the device has 1GB DDR3 cache on it (power-loss protected), can do ~1GB/s of
sustained O_DIRECT sequential writes. But when running pgbench, I can't push
more than ~300MB/s of WAL to it, no matter what I do because of
WALWriteLock.
Hm, interesting. Even if you up wal_buffers to 128MB, use
synchronous_commit = off, and play with wal_writer_delay/flush_after?
I think I've tried things like that, but let me do some proper testing.
I'll report the numbers in a few days.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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