Re: [PERFORM] Questionaire: Common WAL write rates on busy servers.

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
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