Re: GPUSort project

Martijn van Oosterhout wrote:
> On Tue, Apr 11, 2006 at 04:02:07PM -0700, Mischa Sandberg wrote:
>
>>Anybody on this list hear/opine anything pf the GPUSort project for
>>postgresql? I'm working on a radix-sort subcase for tuplesort, and there
>>are similarities.
>>
>>http://www.andrew.cmu.edu/user/ngm/15-823/project/
>
> I've heard it meantioned, didn't know they'd got it working. However,
> none of my database servers have a 3D graphics anywhere near the power
> they suggest in the article.
>
> Is this of practical use for run-of-the-mill video cards?

Short answer: maybe.

Long answer: we're shipping a server (appliance) product built on stock
rackmount hardware, that includes an ATI Rage (8MB) with nothing to do. Much of
what the box does is a single cpu-bound process, sorting maillog extracts. The
GPU is an asset, even at 8MB; the headwork is in mapping/truncating sort keys
down to dense ~32bit prefixes; and in making smooth judgements as to when to
give the job to (a) the GPU (b) quicksort (c) a tiny bitonic sort in the SSE2
registers.

Any of this would apply to postgres, if tuplesort.c can tolerate a preprocessing
step that looks for special cases, and degrades gracefully into the standard
case. I'm guessing that there are enough internal sorts (on oid, for example)
having only small, memcmp-able sort keys, that this is worth adding in.

--
Engineers think that equations approximate reality.
Physicists think that reality approximates the equations.
Mathematicians never make the connection.