Messages in this thread | | | Subject | Re: [PATCH 0/3] cpufreq: Replace timers with utilization update callbacks | From | Steve Muckle <> | Date | Wed, 10 Feb 2016 14:07:51 -0800 |
| |
On 02/10/2016 01:49 PM, Rafael J. Wysocki wrote: >>> If done this way, I guess we may pass rq_clock_task(rq) as the time >>> >> arg to cpufreq_update_util() from there and then the cpu_lock() call >>> >> I've added to this prototype won't be necessary any more. >> > >> > Is it rq_clock_task() or rq_clock()? The former can omit irq time so may >> > gradually fall behind wall clock time, delaying callbacks in cpufreq. > > What matters to us is the difference between the current time and the > time we previously took a sample and there shouldn't be too much > difference between the two in that respect.
Sorry, the reference to wall clock time was unnecessary. I just meant it can lose time, which could cause cpufreq updates to be delayed during irq heavy periods.
> Both are good enough IMO, but I can update the patch to use rq_clock() > if that's preferred.
I do believe rq_clock should be used as workloads such as heavy networking could spend a significant portion of time in interrupts, skewing rq_clock_task significantly, assuming I understand it correctly.
thanks, Steve
| |