Re: Bumping block size to 16K on FreeBSD...

Tom Lane wrote:

>Thomas Swan <tswan(at)idigx(dot)com> writes:
>
>
>>Tom Lane wrote:
>>
>>
>>>I'm a little uncomfortable with introducing a cross-platform variation
>>>in the standard block size.
>>>
>>>
>>>
>>Has anyone looked at changing the default block size across the board
>>and what the performance improvements/penalties might be? Hardware has
>>changed quite a bit over the years.
>>
>>
>
>Not that I know of. That might actually be a more reasonable proposal
>than changing it only on one platform. It would take a fair amount
>of legwork to generate enough evidence to convince people, though ...
>
>
>

I know that you can specify different block sizes for different fs/OS
combinations, notably there were discussions before about running the
WAL on a fat16/32 disks with different performance characteristics.
Also, it's not just an OS abstraction; hardware has changed and evolved
in such a way that the physical disks are reading and writing in larger
chunks. To me it would seem wasteful to not use that bandwidth that is
available for little or no extra cost.

Perhaps testing it for 8K, 16K, 32K, and 64K blocksizes would be a
worthwhile venture. I will have time this weekend with the holiday to
work on some benchmarking for these sizes if only on a linux system.
Tom, what would you consider to be acceptable for a preliminary
investigation? What should I look at: runtime, disk space required
before and after, fsync (on/off)?

--
Thomas