Messages in this thread |  | | | Date | Thu, 30 Nov 2006 07:47:58 +0100 | | From | Ingo Molnar <> | | Subject | Re: [patch 1/4] - Potential performance bottleneck for Linxu TCP |
* David Miller <davem@davemloft.net> wrote:
> > yeah, i like this one. If the problem is "too long locked section", > > then the most natural solution is to "break up the lock", not to > > "boost the priority of the lock-holding task" (which is what the > > proposed patch does). > > Ingo you're mis-read the problem :-)
yeah, the problem isnt too long locked section but "too much time spent holding a lock" and hence opening up ourselves to possible negative side-effects of the scheduler's fairness algorithm when it forces a preemption of that process context with that lock held (and forcing all subsequent packets to be backlogged).
but please read my last mail - i think i'm slowly starting to wake up ;-) I dont think there is any real problem: a tweak to the scheduler that in essence gives TCP-using tasks a preference changes the balance of workloads. Such an explicit tweak is possible already.
furthermore, the tweak allows the shifting of processing from a prioritized process context into a highest-priority softirq context. (it's not proven that there is any significant /net win/ of performance: all that was proven is that if we shift TCP processing from process context into softirq context then TCP throughput of that otherwise penalized process context increases.)
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