On Mon, 2013-09-30 at 18:44 -0700, Linus Torvalds wrote: > On Mon, Sep 30, 2013 at 6:05 PM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote: > > Speaking of spinlock contention, the files->file_lock is a good example. > > > > Multi threaded programs hit this spinlock three times per fd : > > .. do you actually have programs that see contention? Yes, Google-Bug-Id 9072743 for Googlers ;) Basically, we have (many) servers with 10,000,000+ sockets, where this lock contention is a real problem. We use a SOCK_FD_FASTALLOC accept4()/socket() flag to relax POSIX requirements and not having to parse huge bitmap in find_next_zero_bit(fdt->open_fds, fdt->max_fds, fd) (O_FD_FASTALLOC uses a random starting point) I am writing a patch using cmpxchg() to see if I can solve the dup2() 'problem' -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
