Messages in this thread | | | Subject | Re: [PATCH] rcu: restore correct batch limiting | From | Eric Dumazet <> | Date | Thu, 18 Oct 2012 18:10:28 +0200 |
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On Thu, 2012-10-18 at 08:25 -0700, Paul E. McKenney wrote: > On Thu, Oct 18, 2012 at 02:44:50PM +0200, Eric Dumazet wrote:
> > > > Having 2 billions callbacks on one cpu would be problematic, I really > > hope nobody relies on this ;) > > Fair point! ;-) > > But just making everything long makes it quite easy to analyze. > > > I guess the 10/infinity switch should be smarter. > > > > something like the following maybe : > > > > rdp->blimit = max(blimit, rdp->qlen >> 6); > > > > (if queue is big, dont wait to hit 10000 before allowing more items to > > be handled per round) > > The -rt guys would not be amused. :-( > > But for non-realtime use, increasing rcutree.blimit either at boot or > via sysfs could make sense. It is also likely that I will move callback > processing to a kthread at some point, which would allow some additional > flexibility. >
Ah, I now realize the loop can exceed blimit, but is it true for BH variant ? (Not really a problem for 3.6/3.7 kernels, but prior ones)
if (++count >= bl && (need_resched() || (!is_idle_task(current) && !rcu_is_callbacks_kthread()))) break;
I wonder if ksoftirqd should be included as well...
> Furthermore, it would be easy to have one default for non-rt and another > for -rt, if that would help. > > > Signed-off-by: Eric Dumazet <edumazet@google.com> > > > > Please dont forget stable teams. (3.2 + ) > > Added both, please see below! >
Seems fine to me, thanks Paul !
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