Re: Scimark and the sparse matrix mul test
- From: Mike Pall <mike-1403@xxxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Tue, 18 Mar 2014 18:41:19 +0100
Daniel Kolesa wrote:
> As you can see the code is direct rewrite of the Lua inner loop.
> The performance is however vastly different - getting 1800 MFLOPS
> rather than 400 something (just like native SciMark).
The code generated for the innermost loop is more or less optimal.
But for the chosen parameters, it only runs for 5 iterations. Then
the overhead of the trace that runs around it and forms the outer
loop dominates. This trace is not very efficient, since it has to
check lots of assertions, which cannot be hoisted. This is difficult
to improve, since the trace compiler only has local knowledge and
can't infer much about that trace.
--Mike
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