Hi , I've accidently omitted linux-omap in last message, so please here it is again: I think that if someone here understand cpuidle it may lead me to a solution... 1. I'm using TI's kernel 2.6.37 http://git.kernel.org/cgit/linux/kernel/git/tmlind/linux-omap.git/ 2. I think it is related to the menu governer who decides on c-state change. But I'm not sure what and how I need to change so that the ethernet test for small windows will have same performance as without PM. 3. I see that the performace as tested with iperf has the same performace results with large packets but with small packets (smaller then 2000 bytes) there is high degredation (only if cpuidle is used) I also see that the counter for C3(core inactive - not retention yet) state is icremented with the small packet test. Does anyone have any idea why the small packet test results in entering (and exit ) several times the core inactive state? Why does not it happen with big packet test? And what can I do to overcome this degredation? 4. Can anyone try to run iperf with small packet (2000 bytes or below) for checking ethernet bandwidth? And then compare this with results in kernel without power management support? Regards, Ran On Fri, Jul 31, 2015 at 7:40 PM, Robert Nelson <robertcnelson@xxxxxxxxx> wrote: > On Fri, Jul 31, 2015 at 11:29 AM, Ran Shalit <ranshalit@xxxxxxxxx> wrote: >> On Thu, Jul 30, 2015 at 9:49 PM, Ran Shalit <ranshalit@xxxxxxxxx> wrote: >>> Hello, >>> >>> I hope some will have some idea: >>> I am using iperf to check bandwidth and I see that with small tcp >>> windows in the test there is always high degredation in performance >>> compared to version without cpuidle. >>> I've noticed that C3 state (core inactive) is entered several times >>> during the test, which might explaing this degredation. With bug tcp >>> windows it works well (why ?) >>> >>> I would like to ask if there is any idea what I can do to overcome >>> this issue so that there will be no degredation in performance? >>> >>> Thank you, >>> Ran >> >> Does anyone have any idea ? > > Which kernel? Mainline or if ti's which branch? > > Regards, > > -- > Robert Nelson > https://rcn-ee.com/ -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
