Re: [PATCH 0/2] Get rid of ndo_xmit_flush
From: Jesper Dangaard Brouer <hidden>
Date: 2014-08-27 08:37:44
On Wed, 27 Aug 2014 09:48:59 +0200 Jesper Dangaard Brouer [off-list ref] wrote:
Reading Jeremy Eder's blog post: http://www.breakage.org/2012/11/14/processor-max_cstate-intel_idle-max_cstate-and-devcpu_dma_latency/ It seems the best method for disabling these C and P states, and keeping all CPUs in C0/C1 state is doing: # tuned-adm profile latency-performance
[...]
I'm also going to disable Hyper-threading in BIOS, even-though I'm only using one CPU in these tests (I worry that some process running on a sibling could disturb the accuracy).
Disabling Hyper-Threading in BIOS helped the accuracy, now the latency variation is below 0.1ns min:-0.031 and max:0.054 over 120 sec. Still using: # tuned-adm profile latency-performance
Setting: * sudo ethtool -C eth5 rx-usecs 30 Result: * instant rx:1 tx:5603644 pps n:120 average: rx:0 tx:5603317 pps (instant variation TX 0.010 ns (min:-0.132 max:0.114) RX 0.000 ns) * instant rx:1 tx:5599820 pps n:300 average: rx:1 tx:5602382 pps (instant variation TX -0.082 ns (min:-0.209 max:0.114) RX 0.000 ns)
With no HT: * instant rx:1 tx:5597616 pps n:120 average: rx:1 tx:5596283 pps (instant variation TX 0.043 ns (min:-0.031 max:0.054) RX 0.000 ns) With this setup, I think we are ready to measure the effect of our API changes with sufficient accuracy. -- Best regards, Jesper Dangaard Brouer MSc.CS, Sr. Network Kernel Developer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer