Message-ID: <550AF948.3000201@2ndquadrant.com>
Date: Thu, 19 Mar 2015 17:28:56 +0100
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Organization: 2ndQuadrant
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To: pgsql-hackers@postgresql.org
Subject: Re: GSoC - Idea Discussion
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Hi Hitesh,

On 18.3.2015 21:11, hitesh ramani wrote:
> Hello devs,
> 
> As stated earlier I was thinking to propose the integration of
> Postgres and CUDA for faster execution of order by queries thru
> optimizing the sorting code and sorting it with CUDA. I saw and tried
> to run PG Strom and ran into issues. Moreover, PG Strom is
> implemented in OpenCL, not CUDA.

Could you please elaborate more why to choose CUDA, a nvidia-only
technology, rather than OpenCL, supported by much wider range of
companies and projects? Why do you consider OpenCL unsuitable?

Not that CUDA is bad - it certainly works better in some scenarios, but
this is a cost/benefits question, and it only works with devices
manufactured by a single company. That significantly limits the
usefulness of the work, IMHO.

You mention that you ran into issues with PG Strom.  What issues?

> 
> I have hardware to run CUDA and currently I'm at a point where I
> have almost integrated Postgres and CUDA. This opens up gates for a
> lot of features which can be optimized thru CUDA and parallel
> processing, though here I only want to focus on sorting, hence kind
> of feasible for the time period.

Can we see some examples, what this actually means? What you can and
can't do at this point, etc.? Can you share some numbers how this
improves the performance?

> 
> As I did some research, I found CUDA is more efficient in not just
> the parallel performance but data transfer latency too. My idea is to
> create a branch of Postgres with the CUDA integrated code.
>

More efficient than what?

> 
> For the feasibility, I guess it's very much feasible because I've
> almost integrated CUDA execution and the code needs to be optimized
> as per CUDA.

That's really difficult to judge, because you have not provided any
source code, examples or anything else to support this.

> 
> Please give in your valuable suggestions and views on this.

From where I sit, this looks interesting, but rather as a research
project rather than something than can be integrated into PostgreSQL in
a foreseeable future. Not sure that's what GSoC is intended for.

Also, we badly need more details on this - current status, examples, and
especially project plan explaining the scope. It's impossible to say
whether the sort can be implemented within the GSoC time frame.


-- 
Tomas Vondra                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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