https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71744
--- Comment #22 from Gleb Natapov <gleb at scylladb dot com> --- (In reply to torvald from comment #21) > (In reply to Jakub Jelinek from comment #17) > > (In reply to torvald from comment #15) > > > > Similarly, the 64 recursive locks in libc, again, significant amount of > > > > memory > > > > per process that doesn't care about exceptions, > > > > > > That might be reducable if we build custom locks and don't use pthread > > > ones, > > > but we'll at least have 64b per lock. > > > > Right now the lock is I think 40 bytes per lock, which is 64 * 40 bytes per > > process. That is just too much (but of course the 64x locking a recursive > > lock is even worse). > > Remembering more of the discussion we had about this in the past, then even > with the improved rwlock, Gleb reports that there is a slowdown in Gleb's > tests because of cache contention -- which would mean that we may have to > use one cacheline per lock. Right, my patch lacks it, but cache alignment will definitely be an improvement.
