Re: [PATCH] lookup_tag speedup

[Neil Booth <neil at daikokuya dot co dot uk>]

Zack Weinberg wrote:-

> Zack Weinberg <zack at codesourcery dot com> writes:
> 
> > I'd be happy to do this test, but there is no file attached to your
> > message.
> 
> [Devang sent me the test case offline.]
> 
> With a hot cache:
> 
> $ for i in 1 2 3; do /usr/bin/time ./cc1obj.vanilla -O0 -quiet dt.mi; done
> 0:01.32 - 1.26u, 0.05s, 98% - 1198/5404
> 0:01.35 - 1.31u, 0.04s, 99% - 1198/5404
> 0:01.32 - 1.28u, 0.04s, 99% - 1198/5404
> 
> $ for i in 1 2 3; do /usr/bin/time ./cc1obj.c-ids-2 -O0 -quiet dt.mi; done
> 0:00.76 - 0.73u, 0.04s, 100% - 1190/5226
> 0:00.78 - 0.73u, 0.04s,  98% - 1190/5226
> 0:00.78 - 0.71u, 0.06s,  98% - 1190/5226
> 
> I make that a 42% speedup.  At -O2 the figures are similar:
> 
> $ for i in 1 2 3; do /usr/bin/time ./cc1obj.vanilla -O2 -quiet dt.mi; done
> 0:01.37 - 1.32u, 0.03s, 98% - 1290/5464
> 0:01.34 - 1.27u, 0.06s, 98% - 1290/5465
> 0:01.36 - 1.30u, 0.06s, 99% - 1290/5465
> 
> $ for i in 1 2 3; do /usr/bin/time ./cc1obj.c-ids-2 -O2 -quiet dt.mi; done
> 0:00.83 - 0.76u, 0.05s, 97% - 1278/5285
> 0:00.79 - 0.74u, 0.05s, 98% - 1278/5284
> 0:00.79 - 0.74u, 0.04s, 98% - 1278/5284

Cool!  I'm glad we resisted the hash hack.

Neil.