On Fri, Mar 04, 2011 at 11:08:43AM +0000, Alexander Best wrote: > On Fri Mar 4 11, Chagin Dmitry wrote: > > On Thu, Mar 03, 2011 at 09:20:51PM +0000, Alexander Best wrote: > > > hi there, > > > > > > i've been investigating this issue for quite a while now and simply > > > wanted to > > > post some measurements i did. > > > > > > basically there's a massive slowdown when a process triggers a lot of > > > threads > > > which are doing futex operations. the following example is from darren > > > hart's > > > futex test suite (performance/). the slowdown seems to SMP related. here > > > are > > > the measurements running with SMP enabled and with kern.smp.disabled=1: > > > > > > > 1) slowdown is expected behaviour. > > even if the slowdown is to be expected, looking at the screenshot with the > top(1) output it seems obvious that there are issues with the current futex > implementation. >
why do you think it's a problem with the futexes? > > 2) is it possible to run this test suite on FreeBSD? > > i used emulators/linux_dist-gentoo-stage3 to compile the testsuite and then > ran > it natively under freebsd. if you want to i can send you the file. it's > > futex_wait: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), > dynamically linked (uses shared libs), for GNU/Linux 2.6.9, not stripped > ah, tests directly calls sys_futex syscall, so can't be used for umtx/futex comparison :) It would be great to have the same set of tests to compare the linuxulator threads and the native. -- Have fun! chd
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