On Mon, 2014-11-17 at 11:18 -0800, Paul E. McKenney wrote: > On Thu, Nov 13, 2014 at 01:42:12PM +1100, Michael Ellerman wrote: > > On Mon, 2014-11-10 at 14:58 -0600, Paul Clarke wrote: > > > On 11/10/2014 04:08 AM, Benjamin Herrenschmidt wrote: > > > > On Tue, 2014-10-07 at 14:13 -0500, Paul Clarke wrote: > > > >> This patch short-circuits the reset of the decrementer, exiting after > > > >> the decrementer reset, but before the housekeeping tasks if the only > > > >> need for the interrupt is simply to reset it. After this patch, > > > >> the latency spike was measured at about 150 nanoseconds. > > > > > > > > Doesn't this break the irq_work stuff ? We trigger it with a set_dec(1); > > > > and your patch will probably cause it to be skipped... > > > > > > You're right. > > > > Yeah, thanks Ben, that would have been bad. > > > > So we'll need to come up with a different approach. > > If I am understanding this correctly, it underscores the need for more > bits in the decrementer register. :-/
Yes that is the root cause of the problem :) cheers _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
