On 10/26/2010 1:38 PM, Rafael J. Wysocki wrote: > On Tuesday, October 26, 2010, Pierre Tardy wrote: >> On Tue, Oct 26, 2010 at 2:08 PM, Rafael J. Wysocki<rjw@xxxxxxx> wrote: >>> On Tuesday, October 26, 2010, Pierre Tardy wrote: >>>> On Tue, Oct 26, 2010 at 12:58 PM, Peter Zijlstra<peterz@xxxxxxxxxxxxx> wrote: >>>>> On Tue, 2010-10-26 at 11:56 -0500, Pierre Tardy wrote: >>>>>> + trace_runtime_pm_usage(dev, atomic_read(&dev->power.usage_count)+1); >>>>>> atomic_inc(&dev->power.usage_count); >>>>> That's terribly racy.. >>>>> >>>> I know. I'm not proud of this.. As I said, this is preliminary patch. >>>> We dont really need to have this prev_usage. This is just for debug. >>>> It mayprobably endup with something like: >>>> >>>> atomic_inc(&dev->power.usage_count); >>>> + trace_power_device_usage(dev); >>> Well, please tell me what you're trying to achieve. >> Please see attached the kind of pytimechart output I'm trying to >> achieve (yes, this chart is not coherent, seems I'm still missing some >> traces) >> >> We basically want to have a trace point eachtime the usage_counter >> changes, so that I can display nice timecharts, and Arjan can have the >> comm of the process that eventually generated the rpm_get, in order to >> pinpoint it in powertop. >> >> What you dont see in the above two lines is that >> trace_power_device_usage(dev); actually reads the usage_count, as well >> as the driver and device name. > I'm afraid that for this to really work you'd need to put usage_count under a > spinlock along with your trace point, which I'm not really sure I like. > > Besides, I'm not really sure the manipulations of usage_count are worth > tracing. what's most interesting is the 0->1 and 1->0 transitions. _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
