Messages in this thread | | | From | Rick Warner <> | Subject | latency doubled on tg3 device from 2.6.11 to 2.6.12 | Date | Thu, 1 Sep 2005 17:30:51 -0400 |
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Hello, We have been testing latency and bandwidth using our proprietary MPI link checker tool (http://www.microway.com/mpilinkchecker.html) and have found that the latency increased from ~25ms to ~45ms going from 2.6.11 to 2.6.12. 2.6.13 has the same result. We also tried the latest bcm5700 from broadcom (8.2.18) and got the same ~45ms latencies. This was tried on several different opteron and em64t motherboards.
We see 20-25ms latencies with the e1000 driver (with some module options) on all 3 kernel versions. For those interested, the e1000 options used are:
InterruptThrottleRate=0 RxIntDelay=0 TxIntDelay=0 RxAbsIntDelay=0 TxAbsIntDelay=0
Digging through source, it seems that a new locking mechanism for tg3 was put in place in 2.6.12. Is this the likely cause? What can we do to restore our lower latency?
-- Richard Warner Lead Systems Integrator Microway, Inc (508)732-5517 - 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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