Hi Phil Am Montag, 16. April 2018, 10:21:04 CEST schrieb Phil Edworthy: > Hi, > > On 29 March 2018 08:30, Phil Edworthy wrote: > > On 28 March 2018 16:32, Clark Williams wrote: > > > On Wed, 28 Mar 2018 16:56:27 +0200 John Ogness wrote: > > > > On 2018-03-28, Phil Edworthy wrote: > > > > >> > I found that cyclictest results vary from one run to another. > > > > >> > > > > > >> > [...] > > > > >> > > > > > >> > Is it common knowledge that cyclictest results vary so much > > > > >> > from one run to another? Any ideas how to mitigate this? > > [snip] > > > > > > cyclictest -m -n -Sp99 -i200 -h300 -M -D 10h > > [snip] > > > Ok, I have changed the pri to 98, no difference in the results that I can > > see. > > > > I did some overnight tests with 100 runs of cyclictest running for 1 > > minute. Stats below were calculated using stats package from > > http://web.cs.wpi.edu/~claypool/misc/stats/stats.html > > > > 1. Interval fixed to 400us, not using --secalign > > Min: 20 Avg: 37 Max: 187 (avg of 100xMax is 134) > > > > 3. Interval increases from 400 to 499, not using --secalign > > Min: 20 Avg: 37 Max: 211 (avg of 100xMax is 157) > > I've got a bit further with this. > The max latency seen by cyclictest depends on the type of network load used > during the test (duh!). I use a host PC to ping flood the board under test, > however on my board (a low-end ARM board), the *size* of the ping affects > the measured latencies. > Using a ping size of 65506, cyclictest reports significantly higher average > and max latency than if I use the default ping size of 56 bytes. > > In addition to the ping size affecting the results, the cyclictest interval > also affects the latency seen. By running cyclictest for short durations > with the interval sweeping from 400us to 500us, I get significantly higher > max latency than just using an interval of 400us for many hours. > > So, is ping flood a good networking load for cyclictest? > Any suggestions for non-network related loads that can be used whilst > running cyclictest? Then I can determine if it is the GMAC hardware/driver. I would recommend iperf3 for running load tests. You can't be sure how much of these ICMP Packages is handled in hardware. Best Regards Tim -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
