On Mon, May 08, 2017 at 04:07:52AM +0100, Ken Moffat wrote: > On Mon, May 08, 2017 at 12:11:54AM +0100, Ken Moffat wrote: > > ld.bfd ld.gold > run 1 1413.809s 16.2 SBU 1332.698s 15.3 SBU > run 2 1318,971s 15.1 SBU 1339.608s 15.3 SBU > run 3 1390.839s 15.9 SBU 1296.138s 14.8 SBU > > I suspect those are too *few* runs to provide meaningful averages > (and I would probably have to leave the machine totally idle in case > using another term really is upsetting things). At this point, all > I can say is that ld.gold appears to be marginally faster - if you > have built it AND have a slower machine, perhaps it does help. > OK, I've done two more runs.
For clarity, I built first with bfd, then with gold, then second run with bfs, second run with gold, etc. And I dropped the caches before each build. The timings are specific to my machines and the particular config I happened to use. Also, I pass -O2 in CFLAGS, CSSFLAGS: if anything, that should decrease the time spent in compiling if a package prefers more exotic optimizations - and therefore the share of hte time taken by ld would rise. Also, by setting CFLAGS I'm dropping debug info (ISTR firefox drops that by default). Also I made sure that the ld variant I did not want in this run was renamed to ld.whichever.hidden so that the package could not try to use it (firefox has been reputed to use gold if it is available). First, 5 runs of firefox on my AMD A10, where any reliable speedup would be welcome. System is from 20170331. That box only has 4 cores, at times the keyboard was unresponsive, so I typed the results in later. These were all using the performance CPU governor with a 4.11.0 kernel and xscreensaver running after the first couple of minutes. These SBUs are rounded to 0.1. SBU for 5 runs: Avg Min Max ld.bfd 15.0 14.6 15.5 ld.gold 15.0 14.6 15.3 Second, 5 runs of webkitgtk on my intel i7, same system as upthread: SBU for 5 runs: Avg Min Max ld.bfd 38.6 38.1 39.1 ld.gold 38.6 38.4 38.8 Conclusion: gold was developed by google for use on large C++ applications and no doubt in some test context they can prove a benefit. But for ordinary builders any speedup is lost in the overall noise of varying times. It is interesting that for my config of webkitgtk the range of timings with bfd is slightly wider, but the average is identical. I'm going to remove all the things I did to use gold in my own scripts. ĸen -- I live in a city. I know sparrows from starlings. After that everything is a duck as far as I'm concerned. -- Monstrous Regiment -- http://lists.linuxfromscratch.org/listinfo/blfs-dev FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page
