Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, 30 May 2017, Peter Zijlstra wrote: > On Wed, May 24, 2017 at 12:01:50PM -0400, Vince Weaver wrote: > > I already have people really grumpy that you have to have one mmap() page > > per event, meaning you sacrifice one TLB entry for each event you are > > measuring. > > So there is

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, 30 May 2017, Peter Zijlstra wrote: > On Wed, May 24, 2017 at 12:01:50PM -0400, Vince Weaver wrote: > > I already have people really grumpy that you have to have one mmap() page > > per event, meaning you sacrifice one TLB entry for each event you are > > measuring. > > So there is

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> > BTW there's an alternative solution in cycling the NMI watchdog over > > all available CPUs. Then it would eventually cover all. But that's > > less real time friendly than relying on RCU. > > I don't think we need to worry too much about the watchdog being rt > friendly. Robustness is the

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> > BTW there's an alternative solution in cycling the NMI watchdog over > > all available CPUs. Then it would eventually cover all. But that's > > less real time friendly than relying on RCU. > > I don't think we need to worry too much about the watchdog being rt > friendly. Robustness is the

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 10:51:51AM -0700, Andi Kleen wrote: > On Tue, May 30, 2017 at 07:40:14PM +0200, Peter Zijlstra wrote: > > On Tue, May 30, 2017 at 10:22:08AM -0700, Andi Kleen wrote: > > > > > You would only need a single one per system however, not one per CPU. > > > > > RCU already tracks

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 10:51:51AM -0700, Andi Kleen wrote: > On Tue, May 30, 2017 at 07:40:14PM +0200, Peter Zijlstra wrote: > > On Tue, May 30, 2017 at 10:22:08AM -0700, Andi Kleen wrote: > > > > > You would only need a single one per system however, not one per CPU. > > > > > RCU already tracks

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 07:40:14PM +0200, Peter Zijlstra wrote: > On Tue, May 30, 2017 at 10:22:08AM -0700, Andi Kleen wrote: > > > > You would only need a single one per system however, not one per CPU. > > > > RCU already tracks all the CPUs, all we need is a single NMI watchdog > > > > that

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 07:40:14PM +0200, Peter Zijlstra wrote: > On Tue, May 30, 2017 at 10:22:08AM -0700, Andi Kleen wrote: > > > > You would only need a single one per system however, not one per CPU. > > > > RCU already tracks all the CPUs, all we need is a single NMI watchdog > > > > that

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 10:22:08AM -0700, Andi Kleen wrote: > > > You would only need a single one per system however, not one per CPU. > > > RCU already tracks all the CPUs, all we need is a single NMI watchdog > > > that makes sure RCU itself does not get stuck. > > > > > > So we just have to

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 10:22:08AM -0700, Andi Kleen wrote: > > > You would only need a single one per system however, not one per CPU. > > > RCU already tracks all the CPUs, all we need is a single NMI watchdog > > > that makes sure RCU itself does not get stuck. > > > > > > So we just have to

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Wed, May 24, 2017 at 12:01:50PM -0400, Vince Weaver wrote: > I already have people really grumpy that you have to have one mmap() page > per event, meaning you sacrifice one TLB entry for each event you are > measuring. So there is space in that page. We could maybe look at having an array

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Wed, May 24, 2017 at 12:01:50PM -0400, Vince Weaver wrote: > I already have people really grumpy that you have to have one mmap() page > per event, meaning you sacrifice one TLB entry for each event you are > measuring. So there is space in that page. We could maybe look at having an array

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> > You would only need a single one per system however, not one per CPU. > > RCU already tracks all the CPUs, all we need is a single NMI watchdog > > that makes sure RCU itself does not get stuck. > > > > So we just have to find a single watchdog somewhere that can trigger > > NMI. > > But

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> > You would only need a single one per system however, not one per CPU. > > RCU already tracks all the CPUs, all we need is a single NMI watchdog > > that makes sure RCU itself does not get stuck. > > > > So we just have to find a single watchdog somewhere that can trigger > > NMI. > > But

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, 30 May 2017, Stephane Eranian wrote: > On Tue, May 30, 2017 at 2:25 AM, Peter Zijlstra wrote: > > On Sun, May 28, 2017 at 01:31:09PM -0700, Stephane Eranian wrote: > >> Ultimately, I would like to see the watchdog move out of the PMU. That > >> is the only sensible

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, 30 May 2017, Stephane Eranian wrote: > On Tue, May 30, 2017 at 2:25 AM, Peter Zijlstra wrote: > > On Sun, May 28, 2017 at 01:31:09PM -0700, Stephane Eranian wrote: > >> Ultimately, I would like to see the watchdog move out of the PMU. That > >> is the only sensible solution. > >> You

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 9:28 AM, Peter Zijlstra wrote: > On Tue, May 30, 2017 at 06:51:28AM -0700, Andi Kleen wrote: >> On Tue, May 30, 2017 at 11:25:23AM +0200, Peter Zijlstra wrote: >> > On Sun, May 28, 2017 at 01:31:09PM -0700, Stephane Eranian wrote: >> > > Ultimately, I

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 9:28 AM, Peter Zijlstra wrote: > On Tue, May 30, 2017 at 06:51:28AM -0700, Andi Kleen wrote: >> On Tue, May 30, 2017 at 11:25:23AM +0200, Peter Zijlstra wrote: >> > On Sun, May 28, 2017 at 01:31:09PM -0700, Stephane Eranian wrote: >> > > Ultimately, I would like to see the

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 2:25 AM, Peter Zijlstra wrote: > On Sun, May 28, 2017 at 01:31:09PM -0700, Stephane Eranian wrote: >> Ultimately, I would like to see the watchdog move out of the PMU. That >> is the only sensible solution. >> You just need a resource able to

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 2:25 AM, Peter Zijlstra wrote: > On Sun, May 28, 2017 at 01:31:09PM -0700, Stephane Eranian wrote: >> Ultimately, I would like to see the watchdog move out of the PMU. That >> is the only sensible solution. >> You just need a resource able to interrupt on NMI or you handle

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 06:51:28AM -0700, Andi Kleen wrote: > On Tue, May 30, 2017 at 11:25:23AM +0200, Peter Zijlstra wrote: > > On Sun, May 28, 2017 at 01:31:09PM -0700, Stephane Eranian wrote: > > > Ultimately, I would like to see the watchdog move out of the PMU. That > > > is the only

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 06:51:28AM -0700, Andi Kleen wrote: > On Tue, May 30, 2017 at 11:25:23AM +0200, Peter Zijlstra wrote: > > On Sun, May 28, 2017 at 01:31:09PM -0700, Stephane Eranian wrote: > > > Ultimately, I would like to see the watchdog move out of the PMU. That > > > is the only

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 11:25:23AM +0200, Peter Zijlstra wrote: > On Sun, May 28, 2017 at 01:31:09PM -0700, Stephane Eranian wrote: > > Ultimately, I would like to see the watchdog move out of the PMU. That > > is the only sensible solution. > > You just need a resource able to interrupt on NMI or

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Tue, May 30, 2017 at 11:25:23AM +0200, Peter Zijlstra wrote: > On Sun, May 28, 2017 at 01:31:09PM -0700, Stephane Eranian wrote: > > Ultimately, I would like to see the watchdog move out of the PMU. That > > is the only sensible solution. > > You just need a resource able to interrupt on NMI or

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Sun, May 28, 2017 at 01:31:09PM -0700, Stephane Eranian wrote: > Ultimately, I would like to see the watchdog move out of the PMU. That > is the only sensible solution. > You just need a resource able to interrupt on NMI or you handle > interrupt masking in software as has > been proposed on

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Sun, May 28, 2017 at 01:31:09PM -0700, Stephane Eranian wrote: > Ultimately, I would like to see the watchdog move out of the PMU. That > is the only sensible solution. > You just need a resource able to interrupt on NMI or you handle > interrupt masking in software as has > been proposed on

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Wed, May 24, 2017 at 9:01 AM, Vince Weaver wrote: > > On Wed, 24 May 2017, Andi Kleen wrote: > > > > Right, I did not even consider the rdpmc, but yeah, you will get a count > > > that > > > is not relevant to the user visible event. Unless you fake it using the > >

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Wed, May 24, 2017 at 9:01 AM, Vince Weaver wrote: > > On Wed, 24 May 2017, Andi Kleen wrote: > > > > Right, I did not even consider the rdpmc, but yeah, you will get a count > > > that > > > is not relevant to the user visible event. Unless you fake it using the > > > time > > > scaling

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

Hi Kan, [auto build test ERROR on linus/master] [also build test ERROR on v4.12-rc2 next-20170526] [cannot apply to tip/x86/core] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url:

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

Hi Kan, [auto build test ERROR on linus/master] [also build test ERROR on v4.12-rc2 next-20170526] [cannot apply to tip/x86/core] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url:

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> The whole point of the rdpmc() implementation is to be low overhead. > If you have to parse 10 different mmap() fields it starts to defeat the > purpose. You would only use it with ref-cycles of course. So for the normal case there is no overhead. > If the watchdog counter is constantly

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> The whole point of the rdpmc() implementation is to be low overhead. > If you have to parse 10 different mmap() fields it starts to defeat the > purpose. You would only use it with ref-cycles of course. So for the normal case there is no overhead. > If the watchdog counter is constantly

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Wed, 24 May 2017, Andi Kleen wrote: > > Right, I did not even consider the rdpmc, but yeah, you will get a count > > that > > is not relevant to the user visible event. Unless you fake it using the time > > scaling fields there but that's ugly. > > Could add another scaling field to the mmap

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Wed, 24 May 2017, Andi Kleen wrote: > > Right, I did not even consider the rdpmc, but yeah, you will get a count > > that > > is not relevant to the user visible event. Unless you fake it using the time > > scaling fields there but that's ugly. > > Could add another scaling field to the mmap

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> Right, I did not even consider the rdpmc, but yeah, you will get a count that > is not relevant to the user visible event. Unless you fake it using the time > scaling fields there but that's ugly. Could add another scaling field to the mmap page for this. -Andi

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> Right, I did not even consider the rdpmc, but yeah, you will get a count that > is not relevant to the user visible event. Unless you fake it using the time > scaling fields there but that's ugly. Could add another scaling field to the mmap page for this. -Andi

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Mon, May 22, 2017 at 11:39 PM, Peter Zijlstra wrote: > On Mon, May 22, 2017 at 12:28:26PM -0700, Stephane Eranian wrote: >> On Mon, May 22, 2017 at 12:23 PM, Peter Zijlstra >> wrote: >> > On Mon, May 22, 2017 at 04:55:47PM +, Liang, Kan wrote:

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Mon, May 22, 2017 at 11:39 PM, Peter Zijlstra wrote: > On Mon, May 22, 2017 at 12:28:26PM -0700, Stephane Eranian wrote: >> On Mon, May 22, 2017 at 12:23 PM, Peter Zijlstra >> wrote: >> > On Mon, May 22, 2017 at 04:55:47PM +, Liang, Kan wrote: >> >> >> >> >> >> > On Fri, May 19, 2017 at

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Mon, May 22, 2017 at 12:28:26PM -0700, Stephane Eranian wrote: > On Mon, May 22, 2017 at 12:23 PM, Peter Zijlstra wrote: > > On Mon, May 22, 2017 at 04:55:47PM +, Liang, Kan wrote: > >> > >> > >> > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: >

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Mon, May 22, 2017 at 12:28:26PM -0700, Stephane Eranian wrote: > On Mon, May 22, 2017 at 12:23 PM, Peter Zijlstra wrote: > > On Mon, May 22, 2017 at 04:55:47PM +, Liang, Kan wrote: > >> > >> > >> > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > >> > > diff --git

RE: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> > On Mon, May 22, 2017 at 12:23 PM, Peter Zijlstra > wrote: > > On Mon, May 22, 2017 at 04:55:47PM +, Liang, Kan wrote: > >> > >> > >> > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > >> > > diff --git a/arch/x86/events/core.c

RE: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> > On Mon, May 22, 2017 at 12:23 PM, Peter Zijlstra > wrote: > > On Mon, May 22, 2017 at 04:55:47PM +, Liang, Kan wrote: > >> > >> > >> > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > >> > > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c > >> > > index

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Mon, May 22, 2017 at 12:23 PM, Peter Zijlstra wrote: > On Mon, May 22, 2017 at 04:55:47PM +, Liang, Kan wrote: >> >> >> > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: >> > > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index >>

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Mon, May 22, 2017 at 12:23 PM, Peter Zijlstra wrote: > On Mon, May 22, 2017 at 04:55:47PM +, Liang, Kan wrote: >> >> >> > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: >> > > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index >> > > 580b60f..e8b2326

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Mon, May 22, 2017 at 04:55:47PM +, Liang, Kan wrote: > > > > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > > > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index > > > 580b60f..e8b2326 100644 > > > --- a/arch/x86/events/core.c > > > +++

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Mon, May 22, 2017 at 04:55:47PM +, Liang, Kan wrote: > > > > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > > > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index > > > 580b60f..e8b2326 100644 > > > --- a/arch/x86/events/core.c > > > +++

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

Hi, On Mon, May 22, 2017 at 1:30 AM, Peter Zijlstra wrote: > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: >> From: Kan Liang >> >> The CPU ref_cycles can only be used by one user at the same time, >> otherwise a "not counted"

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

Hi, On Mon, May 22, 2017 at 1:30 AM, Peter Zijlstra wrote: > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: >> From: Kan Liang >> >> The CPU ref_cycles can only be used by one user at the same time, >> otherwise a "not counted" error will be displaced. >> [kan]$ sudo

RE: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> On Mon, May 22, 2017 at 11:19:16AM +0200, Peter Zijlstra wrote: > > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > > > @@ -934,6 +938,21 @@ int x86_schedule_events(struct cpu_hw_events > > > *cpuc, int n, int *assign) > > > > for (i = 0; i < n; i++) { > > >

RE: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> On Mon, May 22, 2017 at 11:19:16AM +0200, Peter Zijlstra wrote: > > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > > > @@ -934,6 +938,21 @@ int x86_schedule_events(struct cpu_hw_events > > > *cpuc, int n, int *assign) > > > > for (i = 0; i < n; i++) { > > >

RE: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index > > 580b60f..e8b2326 100644 > > --- a/arch/x86/events/core.c > > +++ b/arch/x86/events/core.c > > @@ -101,6 +101,10 @@ u64 x86_perf_event_update(struct

RE: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

> On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index > > 580b60f..e8b2326 100644 > > --- a/arch/x86/events/core.c > > +++ b/arch/x86/events/core.c > > @@ -101,6 +101,10 @@ u64 x86_perf_event_update(struct

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Mon, May 22, 2017 at 11:19:16AM +0200, Peter Zijlstra wrote: > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > > @@ -934,6 +938,21 @@ int x86_schedule_events(struct cpu_hw_events *cpuc, > > int n, int *assign) > > for (i = 0; i < n; i++) { > >

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Mon, May 22, 2017 at 11:19:16AM +0200, Peter Zijlstra wrote: > On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > > @@ -934,6 +938,21 @@ int x86_schedule_events(struct cpu_hw_events *cpuc, > > int n, int *assign) > > for (i = 0; i < n; i++) { > >

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c > index 580b60f..e8b2326 100644 > --- a/arch/x86/events/core.c > +++ b/arch/x86/events/core.c > @@ -101,6 +101,10 @@ u64 x86_perf_event_update(struct perf_event

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c > index 580b60f..e8b2326 100644 > --- a/arch/x86/events/core.c > +++ b/arch/x86/events/core.c > @@ -101,6 +101,10 @@ u64 x86_perf_event_update(struct perf_event

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > From: Kan Liang > > The CPU ref_cycles can only be used by one user at the same time, > otherwise a "not counted" error will be displaced. > [kan]$ sudo perf stat -x, -e ref-cycles,ref-cycles -- sleep

Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

On Fri, May 19, 2017 at 10:06:21AM -0700, kan.li...@intel.com wrote: > From: Kan Liang > > The CPU ref_cycles can only be used by one user at the same time, > otherwise a "not counted" error will be displaced. > [kan]$ sudo perf stat -x, -e ref-cycles,ref-cycles -- sleep 1 >

[PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

From: Kan Liang The CPU ref_cycles can only be used by one user at the same time, otherwise a "not counted" error will be displaced. [kan]$ sudo perf stat -x, -e ref-cycles,ref-cycles -- sleep 1 1203264,,ref-cycles,513112,100.00 ,,ref-cycles,0,0.00 CPU

[PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

From: Kan Liang The CPU ref_cycles can only be used by one user at the same time, otherwise a "not counted" error will be displaced. [kan]$ sudo perf stat -x, -e ref-cycles,ref-cycles -- sleep 1 1203264,,ref-cycles,513112,100.00 ,,ref-cycles,0,0.00 CPU ref_cycles can only be