On 25.06.2011 11:23, Alexander Korotkov wrote:
On Sat, Jun 25, 2011 at 11:03 AM, Jesper Krogh<jes...@krogh.cc> wrote:
* Wouldn't it be natural to measure the performance benefits of
disc-bound tests in an SSD setup?
Sure, it would be great to run performance tests on SSD drives too.
Unfortunately, I don't have corresponding test platform just now.
Anyone have an SSD setup to run some quick tests with this?
In terms of random IO an SSD can easily be x100 better than rotating
drives and it would be a shame to optimize "against" that world?
Actually, I'm not sure that IO is bottle neck of GiST index build on SSD
drives. It's more likely for me that CPU becomes a bottle neck in this case
and optimizing IO can't give much benefit. But anyway, the value of this
work can be in producing better index in some cases and SSD drive lifetime
economy due to less IO operations.
Yeah, this patch probably doesn't give much benefit on SSDs, not the
order of magnitude improvements it gives on HDDs anyway. I would expect
there to still be a small gain, however. If you look at the comparison
of CPU times on Alexander's tests, the patch doesn't add that much CPU
overhead: about 5% on the point_ops tests. I/O isn't free on SSDs
either, so I would expect the patch to buy back that 5% increase in CPU
overhead by reduced time spent on I/O even on a SSD.
It's much worse on the gist_trgm_ops test case, so this clearly depends
a lot on the opclass, but even that should be possible to optimize quite
a bit.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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