Re: testing HS/SR - 1 vs 2 performance

On Sun, Apr 18, 2010 at 4:22 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On Sun, 2010-04-18 at 13:16 -0700, David Fetter wrote:
>> On Sun, Apr 18, 2010 at 12:01:05PM +0100, Simon Riggs wrote:
>> > On Sun, 2010-04-18 at 08:24 +0100, Simon Riggs wrote:
>> > > On Sat, 2010-04-17 at 18:52 -0400, Tom Lane wrote:
>> > > > Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
>> > > > > What I'm not clear on is why you've used a spinlock everywhere
>> > > > > when only weak-memory thang CPUs are a problem. Why not have a
>> > > > > weak-memory-protect macro that does does nada when the
>> > > > > hardware already protects us? (i.e. a spinlock only for the
>> > > > > hardware that needs it).
>> > > >
>> > > > Well, we could certainly consider that, if we had enough places
>> > > > where there was a demonstrable benefit from it.  I couldn't
>> > > > measure any real slowdown from adding a spinlock in that sinval
>> > > > code, so I didn't propose doing so at the time --- and I'm
>> > > > pretty dubious that this code is sufficiently
>> > > > performance-critical to justify the work, either.
>> > >
>> > > OK, I'll put a spinlock around access to the head of the array.
>> >
>> > v2 patch attached
>>
>> If you've committed this, or any other patch you've sent here,
>> *please* mention so on the same thread.
>
> I haven't yet. I've written two patches - this is a major module rewrite
> and is still under discussion. The other patch has nothing to do with
> this (though I did accidentally include a couple of changes from this
> patch and immediately revoked them).
>
> I will wait awhile to see if anybody has some independent test results.

So, does anyone have a few cycles to test this out? We are down to
handful of remaining open items, so getting this tested and committed
sooner = beta sooner.

...Robert