Re: [RFC] perf: Delayed userspace unwind (Was: [PATCH v3 00/10] x86: ORC unwinder)

2017-07-29 Thread Peter Zijlstra
On Fri, Jul 28, 2017 at 08:35:16PM -0700, Andy Lutomirski wrote: > I haven't checked task_work specifically, but a bunch of the exit work > is permitted to sleep, which is potentially useful. Yes. > If this becomes successful enough that we could eventually deprecate > the old code, I wonder if

Re: [RFC] perf: Delayed userspace unwind (Was: [PATCH v3 00/10] x86: ORC unwinder)

2017-07-29 Thread Peter Zijlstra
On Fri, Jul 28, 2017 at 08:35:16PM -0700, Andy Lutomirski wrote: > I haven't checked task_work specifically, but a bunch of the exit work > is permitted to sleep, which is potentially useful. Yes. > If this becomes successful enough that we could eventually deprecate > the old code, I wonder if

Re: [RFC] perf: Delayed userspace unwind (Was: [PATCH v3 00/10] x86: ORC unwinder)

2017-07-28 Thread Andy Lutomirski
> On Jul 25, 2017, at 7:55 AM, Peter Zijlstra wrote: > >> On Thu, Jul 13, 2017 at 11:19:11AM +0200, Ingo Molnar wrote: >> >> * Peter Zijlstra wrote: >> One gloriously ugly hack would be to delay the userspace unwind to return-to-userspace, at

Re: [RFC] perf: Delayed userspace unwind (Was: [PATCH v3 00/10] x86: ORC unwinder)

2017-07-28 Thread Andy Lutomirski
> On Jul 25, 2017, at 7:55 AM, Peter Zijlstra wrote: > >> On Thu, Jul 13, 2017 at 11:19:11AM +0200, Ingo Molnar wrote: >> >> * Peter Zijlstra wrote: >> One gloriously ugly hack would be to delay the userspace unwind to return-to-userspace, at which point we have a schedulable context

Re: [RFC] perf: Delayed userspace unwind (Was: [PATCH v3 00/10] x86: ORC unwinder)

2017-07-28 Thread Peter Zijlstra
On Fri, Jul 28, 2017 at 04:13:25PM +0200, Jiri Olsa wrote: > On Tue, Jul 25, 2017 at 01:55:12PM +0200, Peter Zijlstra wrote: > > SNIP > > > > > diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c > > index 1b2be63c8528..c98a12f3592c 100644 > > --- a/kernel/events/callchain.c > >

Re: [RFC] perf: Delayed userspace unwind (Was: [PATCH v3 00/10] x86: ORC unwinder)

2017-07-28 Thread Peter Zijlstra
On Fri, Jul 28, 2017 at 04:13:25PM +0200, Jiri Olsa wrote: > On Tue, Jul 25, 2017 at 01:55:12PM +0200, Peter Zijlstra wrote: > > SNIP > > > > > diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c > > index 1b2be63c8528..c98a12f3592c 100644 > > --- a/kernel/events/callchain.c > >

Re: [RFC] perf: Delayed userspace unwind (Was: [PATCH v3 00/10] x86: ORC unwinder)

2017-07-28 Thread Jiri Olsa
On Tue, Jul 25, 2017 at 01:55:12PM +0200, Peter Zijlstra wrote: SNIP > > diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c > index 1b2be63c8528..c98a12f3592c 100644 > --- a/kernel/events/callchain.c > +++ b/kernel/events/callchain.c > @@ -12,6 +12,7 @@ > #include > #include

Re: [RFC] perf: Delayed userspace unwind (Was: [PATCH v3 00/10] x86: ORC unwinder)

2017-07-28 Thread Jiri Olsa
On Tue, Jul 25, 2017 at 01:55:12PM +0200, Peter Zijlstra wrote: SNIP > > diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c > index 1b2be63c8528..c98a12f3592c 100644 > --- a/kernel/events/callchain.c > +++ b/kernel/events/callchain.c > @@ -12,6 +12,7 @@ > #include > #include

[RFC] perf: Delayed userspace unwind (Was: [PATCH v3 00/10] x86: ORC unwinder)

2017-07-25 Thread Peter Zijlstra
On Thu, Jul 13, 2017 at 11:19:11AM +0200, Ingo Molnar wrote: > > * Peter Zijlstra wrote: > > > > One gloriously ugly hack would be to delay the userspace unwind to > > > return-to-userspace, at which point we have a schedulable context and can > > > take > > > faults. >

[RFC] perf: Delayed userspace unwind (Was: [PATCH v3 00/10] x86: ORC unwinder)

2017-07-25 Thread Peter Zijlstra
On Thu, Jul 13, 2017 at 11:19:11AM +0200, Ingo Molnar wrote: > > * Peter Zijlstra wrote: > > > > One gloriously ugly hack would be to delay the userspace unwind to > > > return-to-userspace, at which point we have a schedulable context and can > > > take > > > faults. > > I don't think it's