On Sat, Aug 20, 2011 at 8:51 AM, Torvald Riegel <trie...@redhat.com> wrote: > This adds a futex-based version of the serial lock for use on Linux. The > futex code is basically old code of libitm (it got removed in SVN rev > 157758) with one fix for sysfutex0 on x86_64 and one change that returns > the number of woken processes (futex_wake). > > The gtm_rwlock is similar in concept to the mutex-based version, but > adapted to futexes. It performs better than the mutex-based version. Not > really great yet, but there is no spinning yet, so on contention we'll > always have the overhead of waiting via the futexes. > > Again, RBTree with 1/2/4/6 threads, with different update %: > 0%: 49 89 120 120 > 1%: 48 65 75 80 > 20%: 35 10 10 9 > 100%: 16.5 2.5 2.5 2.5 > > For comparison, the mutex-based version: > 0%: 49 / 90 / 120 > 1%: 47 / 59 / 27 > 20% 34 / 6 / 3 > 100%: 15 / 1 / 1 > > OK for branch? >
For x86. please use #ifdef __x86_64__ # ifndef SYS_futex # define SYS_futex 202 # endif so that it works with x32. See libgomp/config/linux/x86/futex.h Thanks. -- H.J.
