Re: [Valgrind-developers] re: lazy FPU state save/restore

[Julian S. <js...@ac...>]

On Friday 04 October 2002 9:43 pm, Jeremy Fitzhardinge wrote:
> On Fri, 2002-10-04 at 03:51, Julian Seward wrote:
> > How much faster is "significantly faster" ?
>
> OK, I've quantified this now.
>
> Using the attached test program (a matrix multiply extracted from Mesa),
> I'm getting the following timings (fptest compiled with -O; 600MHz PIII
> laptop; --skin=none):
>
> native execution:   0.38s
> baseline valgrind: 65.35s
> lazy-fp valgrind:   4.05s
>
> In other words, Valgrind is currently 172 times slower than running
> native for FP-intensive code; the lazy save-restore improves this by a
> factor of 16 or so to make the valgrind overhead only about 11 times
> slower than native.

Hmm, not bad.  What's the numbers for --skin=memcheck and --skin=addrcheck ?
I know the improvement factor will be a lot less, but I'd still like to know
what it is.

/me is suitably impressed, just in case you were getting any other impression,
btw.

J