On 04/05/13 at 04:16pm, Jakub Jelinek wrote: > On Fri, Apr 05, 2013 at 07:31:55PM +0530, Dhiru Kholia wrote: > > I repeated the benchmarks (mentioned in the above bug report) for > > Firefox 20.0 running on Fedora 18 64-bit. > > Firefox as benchmark doesn't look like a good idea (and I'm really surprised > that we don't compile it as PIE, I thought we've been doing that for years). > The special thing on firefox is that it is really tiny binary (< 64K of > .text) with almost no libraries linked directly (just -lc, -ldl, -lstdc++, > -lpthread and their dependencies (-lm, -lgcc_s)), so indeed the relocation > processing isn't very expensive (only ~ 130 relocations) before reaching > main and prelink can't make it significantly faster. ... I see the problem with using Firefox as a benchmark now. So I started looking for more suitable applications to benchmark and came across Gimp. $ ldd /usr/bin/gimp-2.8 | wc -l 77 $ du -hs /usr/bin/gimp-2.8 5.8M /usr/bin/gimp-2.8 Looks good to use as a benchmark? I ran some benchmarks on various builds of Gimp. Please note that the F18 upstream build has PIE enabled. The benchmarking steps are described at https://github.com/kholia/gimp-bench My Results ========== ~ 39.160s ==> upstream my build ~ 39.750s ==> upstream stock build ~ 40.850s ==> "non-PIE" my build The PIE version turns out to be a bit faster. This seems weird and I can't explain it. Grant repeated the tests independently and his results are below, Grant's Results =============== (No PIE) [gm@localhost gimp-bench]$ time ./launch.sh batch command executed successfully real 2m13.267s user 1m25.577s sys 0m46.474s (PIE) [gm@localhost gimp-bench]$ time ./launch.sh batch command executed successfully real 2m4.328s user 1m22.506s sys 0m44.958s PIE build is faster than the non-PIE build (again!) it seems. ... These results are weird and I can't explain them. Do you have any insights on why the PIE build of Gimp is faster than the non-PIE build? -- Dhiru -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
