On Wed, Apr 17, 2013 at 8:21 PM, Greg Smith <greg@2ndquadrant.com> wrote:
>> The more I read of this thread, the more unhappy I get. It appears that
>> the entire design process is being driven by micro-optimization for CPUs
>> being built by Intel in 2013.
>
> And that's not going to get anyone past review, since all the tests I've
> been doing the last two weeks are on how fast an AMD Opteron 6234 with OS
> cache >> shared_buffers can run this. The main thing I'm still worried
> about is what happens when you have a fast machine that can move memory
> around very quickly and an in-memory workload, but it's hamstrung by the
> checksum computation--and it's not a 2013 Intel machine.
This is a good point. However, I don't completely agree with the
conclusion that we shouldn't be worrying about any of this right now.
While I agree with Tom that it's far too late to think about any
CPU-specific optimizations for 9.3, I have a lot of concern, based on
Ants's numbers, that we've picked a checksum algorithm which is hard
to optimize for performance. If we don't get that fixed for 9.3,
we're potentially looking at inflicting many years of serious
suffering on our user base. If we at least get the *algorithm* right
now, we can worry about optimizing it later. If we get it wrong,
we'll be living with the consequence of that for a really long time.
I wish that we had not scheduled beta quite so soon, as I am sure
there will be even more resistance to changing this after beta. But
I'm having a hard time escaping the conclusion that we're on the edge
of shipping something we will later regret quite deeply. Maybe I'm
wrong?
...Robert