On Sat, Sep 10, 2016 at 09:16:59AM -0700, Christoph Hellwig wrote: > On Thu, Sep 08, 2016 at 09:12:50AM -0700, Todd Kjos wrote: > > In Android systems, the display pipeline relies on low > > latency binder transactions and is therefore sensitive to > > delays caused by contention for the global binder lock. > > Jank is siginificantly reduced by disabling preemption > > while the global binder lock is held. > > That's now how preempt_disable is supposed to use. It is for critical not, that's supposed to be _not_. Just to be absolutely clear, this is NOT how you're supposed to use preempt_disable(). > sections that use per-cpu or similar resources. > > > > > Originally-from: Riley Andrews <riandrews@xxxxxxxxxx> > > Signed-off-by: Todd Kjos <tkjos@xxxxxxxxxx> > > @@ -389,7 +390,11 @@ static int task_get_unused_fd_flags(struct > > binder_proc *proc, int flags) > > rlim_cur = task_rlimit(proc->tsk, RLIMIT_NOFILE); > > unlock_task_sighand(proc->tsk, &irqs); > > > > - return __alloc_fd(files, 0, rlim_cur, flags); > > + preempt_enable_no_resched(); > > + ret = __alloc_fd(files, 0, rlim_cur, flags); > > + preempt_disable(); And the fact that people want to use preempt_enable_no_resched() shows that they're absolutely clueless. This is so broken its not funny. NAK NAK NAK _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
