[cairo] Unreliable cairo-perf results;
was Re: Mark cairo_fixed_t conversion functions with
chris at chris-wilson.co.uk
Thu Mar 22 04:28:41 PDT 2007
Ross Burton (ross at burtonini.com) said:
> You're producing some really interesting looking patches, but I don't
> see any proof that there are performance improvements. I believe there
> are, but I like to see hard numbers! Can you run cairo-perf-diff?
Hmm, would love to provide conclusive evidence showing that this change
improves gcc's output. However I've not found any machine where
cairo-perf gives reliable results, e.g.
ickle at cube:~/src/cairo/perf$ git diff HEAD^ HEAD
diff --git a/src/cairo.h b/src/cairo.h
index a80efde..7701ec4 100644
@@ -43,6 +43,8 @@
+/* force a recompilation */
#define CAIRO_VERSION_ENCODE(major, minor, micro) ( \
((major) * 10000) \
+ ((minor) * 100) \
ickle at cube:~/src/cairo/perf$ ./cairo-perf-diff HEAD^ HEAD -- -i 100
image-rgb paint_image_rgba_source-256 174.08µs 0.25% -> 146.91µs 0.32%: 1.18x speedup
image-rgb paint_image_rgb_over-256 162.36µs 1.22% -> 140.51µs 0.84%: 1.16x speedup
image-rgb paint_similar_rgba_source-256 169.44µs 0.53% -> 147.17µs 0.39%: 1.15x speedup
image-rgb paint_image_rgb_source-256 160.88µs 0.79% -> 140.12µs 0.72%: 1.15x speedup
For the record, that machine is an idle, single processor AMD64 with
1GiB of RAM.
Sorry for the whine - this has been driving me crazy.
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