On Tue, Jul 09, 2019 at 10:58:46AM +0800, Wei Wang wrote: > On 07/08/2019 10:29 PM, Peter Zijlstra wrote: > > Thanks for the comments. > > > > > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > > > index 0ab99c7..19e6593 100644 > > > --- a/include/linux/perf_event.h > > > +++ b/include/linux/perf_event.h > > > @@ -528,6 +528,7 @@ typedef void (*perf_overflow_handler_t)(struct perf_event *, > > > */ > > > #define PERF_EV_CAP_SOFTWARE BIT(0) > > > #define PERF_EV_CAP_READ_ACTIVE_PKG BIT(1) > > > +#define PERF_EV_CAP_NO_COUNTER BIT(2) > > > #define SWEVENT_HLIST_BITS 8 > > > #define SWEVENT_HLIST_SIZE (1 << SWEVENT_HLIST_BITS) > > > @@ -895,6 +896,13 @@ extern int perf_event_refresh(struct perf_event *event, int refresh); > > > extern void perf_event_update_userpage(struct perf_event *event); > > > extern int perf_event_release_kernel(struct perf_event *event); > > > extern struct perf_event * > > > +perf_event_create(struct perf_event_attr *attr, > > > + int cpu, > > > + struct task_struct *task, > > > + perf_overflow_handler_t overflow_handler, > > > + void *context, > > > + bool counter_assignment); > > > +extern struct perf_event * > > > perf_event_create_kernel_counter(struct perf_event_attr *attr, > > > int cpu, > > > struct task_struct *task, > > Why the heck are you creating this wrapper nonsense? > > (please see early discussions: https://lkml.org/lkml/2018/9/20/868) > I thought we agreed that the perf event created here don't need to consume > an extra counter. That's almost a year ago; I really can't remember that and you didn't put any of that in your Changelog to help me remember. (also please use: https://lkml.kernel.org/r/$msgid style links) > In the previous version, we added a "no_counter" bit to perf_event_attr, and > that will be exposed to user ABI, which seems not good. > (https://lkml.org/lkml/2019/2/14/791) > So we wrap a new kernel API above to support this. > > Do you have a different suggestion to do this? > (exclude host/guest just clears the enable bit when on VM-exit/entry, > still consumes the counter) Just add an argument to perf_event_create_kernel_counter() ?
