On 03/31/2015 09:01 PM, Benjamin Herrenschmidt wrote:
On Tue, 2015-03-31 at 14:06 -0400, Sowmini Varadhan wrote:
Having bravely said that..
the IB team informs me that they see a 10% degradation using
the spin_lock as opposed to the trylock.
one path going forward is to continue processing this patch-set
as is. I can investigate this further, and later revise the spin_lock
to the trylock, after we are certain that it is good/necessary.
Have they tried using more pools instead ?
we just tried 32 instead of 16, no change to perf.
Looks like their current bottleneck is the find_next_zero_bit (they
can get a 2X perf improvement with the lock fragmentation, but are
then hitting a new ceiling, even with the trylock version)
I'm starting to wonder if some approximation of dma premapped
buffers may be needed. Doing a map/unmap on each packet is expensive.
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