Re: [RFC PATCH 0/5] net: low latency Ethernet device polling

From: Ben Greear
Date: Wed Feb 27 2013 - 16:44:13 EST

On 02/27/2013 12:40 PM, Eliezer Tamir wrote:
On 27/02/2013 21:58, Rick Jones wrote:
On 02/27/2013 09:55 AM, Eliezer Tamir wrote:

Performance numbers:
Kernel Config C3/6 rx-usecs TCP UDP
3.8rc6 typical off adaptive 37k 40k
3.8rc6 typical off 0* 50k 56k
3.8rc6 optimized off 0* 61k 67k
3.8rc6 optimized on adaptive 26k 29k
patched typical off adaptive 70k 78k
patched optimized off adaptive 79k 88k
patched optimized off 100 84k 92k
patched optimized on adaptive 83k 91k
*rx-usecs=0 is usually not useful in a production environment.

I would think that latency-sensitive folks would be using rx-usecs=0 in
production - at least if the NIC in use didn't have low enough latency
with its default interrupt coalescing/avoidance heuristics.

It will only work well if you have no bulk traffic on the same port as the low latency traffic at all.

Have you done any tests for bulk throughput with busy-poll? Yes, it will eat a core,
but that might be worth it in some cases if there was significant throughput increase...


Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc

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