On Thu, 2011-01-27 at 22:59 +0200, Kostik Belousov wrote: > On Thu, Jan 27, 2011 at 08:50:48PM +0000, Devin Teske wrote: > > On Thu, 2011-01-27 at 22:31 +0200, Kostik Belousov wrote: > > > > > On Thu, Jan 27, 2011 at 12:37:54PM -0500, Mark Saad wrote: > > > > On Thu, Jan 27, 2011 at 6:05 AM, David Naylor > > > > <[email protected]> wrote: > > > > > On Wednesday 26 January 2011 06:49:11 Alexander Kabaev wrote: > > > > >> On Tue, 25 Jan 2011 21:40:42 -0500 > > > > >> > > > > >> Mark Saad <[email protected]> wrote: > > > > >> > Hello Hackers > > > > >> > > > > > >> > The NetBSD folks have a nice improvement with the rtld-elf > > > > >> > subsystem, > > > > >> > known as "Negative Symbol Cache" . > > > > >> > > > > > >> > http://blog.netbsd.org/tnf/entry/netbsd_runtime_linker_gains_negative > > > > >> > > > > > >> > Roy Marples roy@ has a simple write up of the change. > > > > >> > > > > > >> > I took the basic idea from FreeBSD, but improved the performance > > > > >> > drastically. Basically, the huge win is by caching both breadth and > > > > >> > depth of the needed/weak symbol lookup. > > > > >> > Easiest to think of a,b,c,d as a matrix and FreeBSD just cache a > > > > >> > row > > > > >> > where we cache both rows and columns. > > > > >> > > > > > >> > Has anyone looked into porting the changes back to FreeBSD ? The > > > > >> > improvement on load time for things like firefox, openoffice, and > > > > >> > java > > > > >> > is huge on NetBSD. It looks like this change could improve load > > > > >> > times > > > > >> > on FreeBSD in the same ways. > > > > >> > > > > >> This is a second time someone posts this to public mailing list and > > > > >> curiously enough is a second time it suggested that someone else is > > > > >> to > > > > >> do the investigation. From the quick look, the commit in question is > > > > >> more or less a direct rip-off of Donelists we had for ages and as > > > > >> such is completely over-hyped. The only extra quirk that said commit > > > > >> does is an optimization of a dlsym() call, which is hardly ever in > > > > >> critical performance path. Said optimization is trivial and easy to > > > > >> try. Here you have it: > > > > >> http://people.freebsd.org/~kan/rtld-symlook-depth.diff > > > > >> > > > > >> Since it only applies to dlsym, it only affects programs that are > > > > >> heavy > > > > >> plugin users, which I suppose is the category OpenOffice and firefox > > > > >> both fall into. Care to do some benchmarks with and without the > > > > >> patch and report the results? I frankly doubt that you'll see any > > > > >> noticeable difference compared to our stock rtld's performance. > > > > > > > > > > I benchmarked the impact said patch has on the boot-time of my > > > > > system. I > > > > > timed the boot-time to when KDE launches autostart programs and once > > > > > all > > > > > programs have loaded (I run a few extra programs, such as amarok). > > > > > The latter > > > > > measure requires human action thus it has extra, human, variance in > > > > > its > > > > > measure. > > > > > > > > > > I tried an older version of rtld (about 2 months old), current > > > > > version of rtld > > > > > and the new (patched) rtld. I ran each test three times. There was > > > > > little > > > > > variance in the tests and I am confident that there is no difference > > > > > between > > > > > the different rtld versions and my boot-time. > > > > > > > > > > Here is a summary of my boot times (in seconds). First measure is > > > > > when KDE > > > > > autostarts programs, the latter is when I determined when all > > > > > programs had > > > > > launched. > > > > > rtld-old: 69 96 > > > > > rtld: 69 94 > > > > > rtld-new: 69 94 > > > > > > > > > > Please note that kernel boot time is approximately 10 seconds and kdm > > > > > is > > > > > delayed by about 10 seconds thus 20 seconds can be removed from above > > > > > numbers > > > > > to determine non-kernel boot wall-time. > > > > > > > > > > I would like to add that the blog entry claims a substantial > > > > > improvement for > > > > > some use cases. Is it not worth to optimism these fringe cases as > > > > > one mans > > > > > fringe case is another mans normal case (or woman as one prefers)? > > > > > > > > > > > > > > > > > So I figured out how to properly fit my foot in my mouth and set out > > > > to retesting this on netbsd. > > > > Turns out that in most cases the speed up is not as dramatic. > > > > > > > > Firefox 3.6.16 on amd64 > > > > > > > > old ld.elf_so: 4.07 seconds > > > > new ld.elf_so: 3.89 seconds > > > > > > > > Openoffice 3.1 on amd64 > > > > > > > > old ld.elf_so: 2.67 seconds > > > > new ld.elf_so: 2.60 seconds > > > > > > > > I am slightly perturbed that I can start openoffice faster then I can > > > > start firefox, oh well. > > > > > > Can you, please, satisfy my curiousity ? How did you fixated the moment > > > of finishing the startup of interactive applications like ff or oo ? > > > > > > Probably did something like this: > > > > time sh -c '( firefox & ); sleep 10000000' > > > > and then pressed Ctrl-C when he felt that firefox was finished loading. > > The moment Ctrl-C is pressed, time(1) shows how long it ran up until you > > pressed Ctrl-C. > > NOTE: Pressing Ctrl-C will not terminate the firefox instance. > > You cannot have 1/100 of seconds precision with this method. > This is why I am asking, seeing < 0.1 seconds difference. > Not to mention some methodical questions, like whether the caches were > warmed before the measurement by several runs before the actual > test.
Really? $ time sh -c '( firefox & ); sleep 10000000' ^C real 0m5.270s user 0m0.000s sys 0m0.005s I'd call that 1/100th of a second precision, wouldn't you? HINT: Try using bash instead of csh. -- Devin _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[email protected]"
