Messages in this thread | | | Date | Sat, 10 Mar 2012 11:32:16 +0800 | Subject | Re: [RFC PATCH 5/6] implement per-cpu&per-domain state machine call_srcu() | From | Lai Jiangshan <> |
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On Fri, Mar 9, 2012 at 3:58 AM, Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote: > On Tue, Mar 06, 2012 at 04:34:53PM +0100, Peter Zijlstra wrote: >> On Tue, 2012-03-06 at 23:12 +0800, Lai Jiangshan wrote: >> > On Tue, Mar 6, 2012 at 7:16 PM, Peter Zijlstra <peterz@infradead.org> wrote: >> > > On Tue, 2012-03-06 at 17:57 +0800, Lai Jiangshan wrote: >> > >> srcu_head is bigger, it is worth, it provides more ability and simplify >> > >> the srcu code. >> > > >> > > Dubious claim.. memory footprint of various data structures is deemed >> > > important. rcu_head is 16 bytes, srcu_head is 32 bytes. I think it would >> > > be real nice not to have two different callback structures and not grow >> > > them as large. >> > >> > CC: tj@kernel.org >> > It could be better if workqueue also supports 2*sizeof(long) work callbacks. >> >> That's going to be very painful if at all possible. >> >> > I prefer ability/functionality a little more, it eases the caller's pain. >> > preemptible callbacks also eases the pressure of the whole system. >> > But I'm also ok if we limit the srcu-callbacks in softirq. >> >> You don't have to use softirq, you could run a complete list from a >> single worklet. Just keep the single linked rcu_head list and enqueue a >> static (per-cpu) worker to process the entire list. > > I like the idea of SRCU using rcu_head. I am a little concerned about > what happens when there are lots of SRCU callbacks, but am willing to > wait to solve those problems until the situation arises. > > But I guess I should ask... Peter, what do you expect the maximum > call_srcu() rate to be in your use cases? If tens of thousands are > possible, some adjustments will be needed.
Different from RCU(global domain), SRCU is separated by domains, I think the rate is not high for a given domain, but the real answer depends on the practice.
> > Thanx, Paul > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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