| From: | Alexander Staubo <alex(at)purefiction(dot)net> |
|---|---|
| To: | Michael Stone <mstone+postgres(at)mathom(dot)us> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: New to PostgreSQL, performance considerations |
| Date: | 2006-12-12 14:32:03 |
| Message-ID: | 42B14BCF-B745-4F94-B5EA-97997744A4D5@purefiction.net |
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| Lists: | pgsql-performance |
On Dec 12, 2006, at 13:32 , Michael Stone wrote:
> On Tue, Dec 12, 2006 at 12:29:29PM +0100, Alexander Staubo wrote:
>> I suspect the hardware's real maximum performance of the system
>> is ~150 tps, but that the LSI's write cache is buffering the
>> writes. I would love to validate this hypothesis, but I'm not
>> sure how.
>
> With fsync off? The write cache shouldn't really matter in that
> case. (And for this purpose that's probably a reasonable
> configuration.)
No, fsync=on. The tps values are similarly unstable with fsync=off,
though -- I'm seeing bursts of high tps values followed by low-tps
valleys, a kind of staccato flow indicative of a write caching being
filled up and flushed.
Alexander.
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