[PATCHv2 0/3] Update cpupower and make it more accurate

[PATCHv2 0/3] Update cpupower and make it more accurate

[Natarajan, Janakarajan]

This patchset updates cpupower to make it more accurate by removing
the userspace to kernel transitions and read_msr initiated IPI delays.

The first patch does a little re-arrangement of variables in the
cpuidle_monitor struct to prepare for a new flag.

The second patch introduces a per_cpu_schedule flag which, when set,
will allow cpupower to move to each of the cpus in the system. The
advantage of this is that the IPI latency is removed when reading
the APERF/MPERF registers, since an IPI is not generated for rdmsrs
when the source and destination cpus are the same for the IPI.

The third patch introduces the RDPRU instruction, which will allow
cpupower to not use the msr module for APERF/MPERF register reads.
This will remove the userspace to kernel transition delays when
reading the APERF/MPERF registers.

v1->v2:
* Added cover letter.
* Used bind_cpu instead of rewriting the same code.
* Moved needs_root to flag sub-struct.
* Introduced per_cpu_schedule flag.

Janakarajan Natarajan (3):
  cpupower: Move needs_root variable into a sub-struct
  cpupower: mperf_monitor: Introduce per_cpu_schedule flag
  cpupower: mperf_monitor: Update cpupower to use the RDPRU instruction

 tools/power/cpupower/utils/helpers/cpuid.c    |  4 ++
 tools/power/cpupower/utils/helpers/helpers.h  |  1 +
 .../utils/idle_monitor/amd_fam14h_idle.c      |  2 +-
 .../utils/idle_monitor/cpuidle_sysfs.c        |  2 +-
 .../utils/idle_monitor/cpupower-monitor.c     |  2 +-
 .../utils/idle_monitor/cpupower-monitor.h     |  5 +-
 .../utils/idle_monitor/hsw_ext_idle.c         |  2 +-
 .../utils/idle_monitor/mperf_monitor.c        | 64 +++++++++++++++----
 .../cpupower/utils/idle_monitor/nhm_idle.c    |  2 +-
 .../cpupower/utils/idle_monitor/snb_idle.c    |  2 +-
 10 files changed, 68 insertions(+), 18 deletions(-)

-- 
2.17.1

[PATCHv2 1/3] cpupower: Move needs_root variable into a sub-struct

[Natarajan, Janakarajan]

Move the needs_root variable into a sub-struct. This is in preparation
for adding a new flag for cpuidle_monitor.

Update all uses of the needs_root variable to reflect this change.

Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
---
 tools/power/cpupower/utils/idle_monitor/amd_fam14h_idle.c  | 2 +-
 tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c    | 2 +-
 tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c | 2 +-
 tools/power/cpupower/utils/idle_monitor/cpupower-monitor.h | 4 +++-
 tools/power/cpupower/utils/idle_monitor/hsw_ext_idle.c     | 2 +-
 tools/power/cpupower/utils/idle_monitor/mperf_monitor.c    | 2 +-
 tools/power/cpupower/utils/idle_monitor/nhm_idle.c         | 2 +-
 tools/power/cpupower/utils/idle_monitor/snb_idle.c         | 2 +-
 8 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/tools/power/cpupower/utils/idle_monitor/amd_fam14h_idle.c b/tools/power/cpupower/utils/idle_monitor/amd_fam14h_idle.c
index 3f893b99b337..33dc34db4f3c 100644
--- a/tools/power/cpupower/utils/idle_monitor/amd_fam14h_idle.c
+++ b/tools/power/cpupower/utils/idle_monitor/amd_fam14h_idle.c
@@ -328,7 +328,7 @@ struct cpuidle_monitor amd_fam14h_monitor = {
 	.stop			= amd_fam14h_stop,
 	.do_register		= amd_fam14h_register,
 	.unregister		= amd_fam14h_unregister,
-	.needs_root		= 1,
+	.flags.needs_root	= 1,
 	.overflow_s		= OVERFLOW_MS / 1000,
 };
 #endif /* #if defined(__i386__) || defined(__x86_64__) */
diff --git a/tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c b/tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c
index f634aeb65c5f..3c4cee160b0e 100644
--- a/tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c
+++ b/tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c
@@ -207,6 +207,6 @@ struct cpuidle_monitor cpuidle_sysfs_monitor = {
 	.stop			= cpuidle_stop,
 	.do_register		= cpuidle_register,
 	.unregister		= cpuidle_unregister,
-	.needs_root		= 0,
+	.flags.needs_root	= 0,
 	.overflow_s		= UINT_MAX,
 };
diff --git a/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c b/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c
index d3c3e6e7aa26..6d44fec55ad5 100644
--- a/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c
+++ b/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c
@@ -408,7 +408,7 @@ int cmd_monitor(int argc, char **argv)
 		dprint("Try to register: %s\n", all_monitors[num]->name);
 		test_mon = all_monitors[num]->do_register();
 		if (test_mon) {
-			if (test_mon->needs_root && !run_as_root) {
+			if (test_mon->flags.needs_root && !run_as_root) {
 				fprintf(stderr, _("Available monitor %s needs "
 					  "root access\n"), test_mon->name);
 				continue;
diff --git a/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.h b/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.h
index a2d901d3bfaf..9b612d999660 100644
--- a/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.h
+++ b/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.h
@@ -60,7 +60,9 @@ struct cpuidle_monitor {
 	struct cpuidle_monitor* (*do_register) (void);
 	void (*unregister)(void);
 	unsigned int overflow_s;
-	int needs_root;
+	struct {
+		unsigned int needs_root:1;
+	} flags;
 };
 
 extern long long timespec_diff_us(struct timespec start, struct timespec end);
diff --git a/tools/power/cpupower/utils/idle_monitor/hsw_ext_idle.c b/tools/power/cpupower/utils/idle_monitor/hsw_ext_idle.c
index 7c7451d3f494..885740a654e6 100644
--- a/tools/power/cpupower/utils/idle_monitor/hsw_ext_idle.c
+++ b/tools/power/cpupower/utils/idle_monitor/hsw_ext_idle.c
@@ -188,7 +188,7 @@ struct cpuidle_monitor intel_hsw_ext_monitor = {
 	.stop			= hsw_ext_stop,
 	.do_register		= hsw_ext_register,
 	.unregister		= hsw_ext_unregister,
-	.needs_root		= 1,
+	.flags.needs_root	= 1,
 	.overflow_s		= 922000000 /* 922337203 seconds TSC overflow
 					       at 20GHz */
 };
diff --git a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
index 44806a6dae11..7cae74202a4d 100644
--- a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
+++ b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
@@ -333,7 +333,7 @@ struct cpuidle_monitor mperf_monitor = {
 	.stop			= mperf_stop,
 	.do_register		= mperf_register,
 	.unregister		= mperf_unregister,
-	.needs_root		= 1,
+	.flags.needs_root	= 1,
 	.overflow_s		= 922000000 /* 922337203 seconds TSC overflow
 					       at 20GHz */
 };
diff --git a/tools/power/cpupower/utils/idle_monitor/nhm_idle.c b/tools/power/cpupower/utils/idle_monitor/nhm_idle.c
index be7256696a37..114271165182 100644
--- a/tools/power/cpupower/utils/idle_monitor/nhm_idle.c
+++ b/tools/power/cpupower/utils/idle_monitor/nhm_idle.c
@@ -208,7 +208,7 @@ struct cpuidle_monitor intel_nhm_monitor = {
 	.stop			= nhm_stop,
 	.do_register		= intel_nhm_register,
 	.unregister		= intel_nhm_unregister,
-	.needs_root		= 1,
+	.flags.needs_root	= 1,
 	.overflow_s		= 922000000 /* 922337203 seconds TSC overflow
 					       at 20GHz */
 };
diff --git a/tools/power/cpupower/utils/idle_monitor/snb_idle.c b/tools/power/cpupower/utils/idle_monitor/snb_idle.c
index 968333571cad..df8b223cc096 100644
--- a/tools/power/cpupower/utils/idle_monitor/snb_idle.c
+++ b/tools/power/cpupower/utils/idle_monitor/snb_idle.c
@@ -192,7 +192,7 @@ struct cpuidle_monitor intel_snb_monitor = {
 	.stop			= snb_stop,
 	.do_register		= snb_register,
 	.unregister		= snb_unregister,
-	.needs_root		= 1,
+	.flags.needs_root	= 1,
 	.overflow_s		= 922000000 /* 922337203 seconds TSC overflow
 					       at 20GHz */
 };
-- 
2.17.1

[PATCHv2 2/3] cpupower: mperf_monitor: Introduce per_cpu_schedule flag

[Natarajan, Janakarajan]

The per_cpu_schedule flag is used to move the cpupower process to the cpu
on which we are looking to read the APERF/MPERF registers.

This prevents IPIs from being generated by read_msr()s as we are already
on the cpu of interest.

Ex: If cpupower is running on CPU 0 and we execute

    read_msr(20, MSR_APERF, val) then,
    read_msr(20, MSR_MPERF, val)

    the msr module will generate an IPI from CPU 0 to CPU 20 to query
    for the MSR_APERF and then the MSR_MPERF in separate IPIs.

This delay, caused by IPI latency, between reading the APERF and MPERF
registers may cause both of them to go out of sync.

The use of the per_cpu_schedule flag reduces the probability of this
from happening. It comes at the cost of a negligible increase in cpu
consumption caused by the migration of cpupower across each of the
cpus of the system.

Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
---
 .../utils/idle_monitor/cpupower-monitor.h     |  1 +
 .../utils/idle_monitor/mperf_monitor.c        | 42 ++++++++++++++-----
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.h b/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.h
index 9b612d999660..5b5eb1da0cce 100644
--- a/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.h
+++ b/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.h
@@ -62,6 +62,7 @@ struct cpuidle_monitor {
 	unsigned int overflow_s;
 	struct {
 		unsigned int needs_root:1;
+		unsigned int per_cpu_schedule:1;
 	} flags;
 };
 
diff --git a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
index 7cae74202a4d..afb2e6f8edd3 100644
--- a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
+++ b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
@@ -86,15 +86,35 @@ static int mperf_get_tsc(unsigned long long *tsc)
 	return ret;
 }
 
+static int get_aperf_mperf(int cpu, unsigned long long *aval,
+				    unsigned long long *mval)
+{
+	int ret;
+
+	/*
+	 * Running on the cpu from which we read the registers will
+	 * prevent APERF/MPERF from going out of sync because of IPI
+	 * latency introduced by read_msr()s.
+	 */
+	if (mperf_monitor.flags.per_cpu_schedule) {
+		if (bind_cpu(cpu))
+			return 1;
+	}
+
+	ret  = read_msr(cpu, MSR_APERF, aval);
+	ret |= read_msr(cpu, MSR_MPERF, mval);
+
+	return ret;
+}
+
 static int mperf_init_stats(unsigned int cpu)
 {
-	unsigned long long val;
+	unsigned long long aval, mval;
 	int ret;
 
-	ret = read_msr(cpu, MSR_APERF, &val);
-	aperf_previous_count[cpu] = val;
-	ret |= read_msr(cpu, MSR_MPERF, &val);
-	mperf_previous_count[cpu] = val;
+	ret = get_aperf_mperf(cpu, &aval, &mval);
+	aperf_previous_count[cpu] = aval;
+	mperf_previous_count[cpu] = mval;
 	is_valid[cpu] = !ret;
 
 	return 0;
@@ -102,13 +122,12 @@ static int mperf_init_stats(unsigned int cpu)
 
 static int mperf_measure_stats(unsigned int cpu)
 {
-	unsigned long long val;
+	unsigned long long aval, mval;
 	int ret;
 
-	ret = read_msr(cpu, MSR_APERF, &val);
-	aperf_current_count[cpu] = val;
-	ret |= read_msr(cpu, MSR_MPERF, &val);
-	mperf_current_count[cpu] = val;
+	ret = get_aperf_mperf(cpu, &aval, &mval);
+	aperf_current_count[cpu] = aval;
+	mperf_current_count[cpu] = mval;
 	is_valid[cpu] = !ret;
 
 	return 0;
@@ -305,6 +324,9 @@ struct cpuidle_monitor *mperf_register(void)
 	if (init_maxfreq_mode())
 		return NULL;
 
+	if (cpupower_cpu_info.vendor == X86_VENDOR_AMD)
+		mperf_monitor.flags.per_cpu_schedule = 1;
+
 	/* Free this at program termination */
 	is_valid = calloc(cpu_count, sizeof(int));
 	mperf_previous_count = calloc(cpu_count, sizeof(unsigned long long));
-- 
2.17.1

Re: [PATCHv2 2/3] cpupower: mperf_monitor: Introduce per_cpu_schedule flag

[Thomas Renninger]

Hi Natarajan,

sorry for answering that late.
I post on top as it doesn't fit to the patch context:

While I like the 2 other patches, especially the first preparing for
a generic "ensure to always run on the measured CPU at measure time" 
interface..., this patch does make use of it in a very static manner.

I then tried to get this more generic..., without any outcome for now.

If someone likes to play with this, my idea would be:

- the monitors need cpu_start() and cpu_stop() callbacks to register
- either start(), stop() and/or cpu_start(), cpu_stop() callbacks have to
  be provided by a monitor.
- current behavior is only start/stop which means the whole per_cpu logic
  resides inside the monitor
- if cpu_start/cpu_stop is provided, iterating over all cpus is done in
  fork_it and general start/stop functions are an optionally entry point
  before and after the per_cpu calls.

Then the cpu binding can be done from outside.
Another enhancement could be then to fork as many processes as there are CPUs
in case of per_cpu_schedule (or an extra param/flag) and then:

- Bind these forked processes to each cpu.
- Execute start measures via the forked processes on each cpu
- Execute test executable (which runs in yet another fork as done already)
- Execute stop measures via the forked processes on each cpu

This should be ideal environment to not interfere with the tested executable.
It would also allow a nicer program structure.

Just some ideas. But no time right now to look deeper into this.

I'll ack on the first summarizing commit message.


    Thomas

Re: [PATCHv2 2/3] cpupower: mperf_monitor: Introduce per_cpu_schedule flag

[shuah]

On 10/25/19 4:39 AM, Thomas Renninger wrote:
> Hi Natarajan,
> 
> sorry for answering that late.
> I post on top as it doesn't fit to the patch context:
> 
> While I like the 2 other patches, especially the first preparing for
> a generic "ensure to always run on the measured CPU at measure time"
> interface..., this patch does make use of it in a very static manner.
> 
> I then tried to get this more generic..., without any outcome for now.
> 
> If someone likes to play with this, my idea would be:
> 
> - the monitors need cpu_start() and cpu_stop() callbacks to register
> - either start(), stop() and/or cpu_start(), cpu_stop() callbacks have to
>    be provided by a monitor.
> - current behavior is only start/stop which means the whole per_cpu logic
>    resides inside the monitor
> - if cpu_start/cpu_stop is provided, iterating over all cpus is done in
>    fork_it and general start/stop functions are an optionally entry point
>    before and after the per_cpu calls.
> 
> Then the cpu binding can be done from outside.
> Another enhancement could be then to fork as many processes as there are CPUs
> in case of per_cpu_schedule (or an extra param/flag) and then:
> 
> - Bind these forked processes to each cpu.
> - Execute start measures via the forked processes on each cpu
> - Execute test executable (which runs in yet another fork as done already)
> - Execute stop measures via the forked processes on each cpu
> 
> This should be ideal environment to not interfere with the tested executable.
> It would also allow a nicer program structure.
> 

It will be good to capture these ideas in the ToDo file.

Natarajan! WOuld you like to send a patch updating the ToDo file with
these ideas?

thanks,
-- Shuah

Re: [PATCHv2 2/3] cpupower: mperf_monitor: Introduce per_cpu_schedule flag

[Natarajan, Janakarajan]

On 10/25/2019 10:33 AM, shuah wrote:
> On 10/25/19 4:39 AM, Thomas Renninger wrote:
>> Hi Natarajan,
>>
>> sorry for answering that late.
>> I post on top as it doesn't fit to the patch context:
>>
>> While I like the 2 other patches, especially the first preparing for
>> a generic "ensure to always run on the measured CPU at measure time"
>> interface..., this patch does make use of it in a very static manner.
>>
>> I then tried to get this more generic..., without any outcome for now.
>>
>> If someone likes to play with this, my idea would be:
>>
>> - the monitors need cpu_start() and cpu_stop() callbacks to register
>> - either start(), stop() and/or cpu_start(), cpu_stop() callbacks 
>> have to
>>    be provided by a monitor.
>> - current behavior is only start/stop which means the whole per_cpu 
>> logic
>>    resides inside the monitor
>> - if cpu_start/cpu_stop is provided, iterating over all cpus is done in
>>    fork_it and general start/stop functions are an optionally entry 
>> point
>>    before and after the per_cpu calls.
>>
>> Then the cpu binding can be done from outside.
>> Another enhancement could be then to fork as many processes as there 
>> are CPUs
>> in case of per_cpu_schedule (or an extra param/flag) and then:
>>
>> - Bind these forked processes to each cpu.
>> - Execute start measures via the forked processes on each cpu
>> - Execute test executable (which runs in yet another fork as done 
>> already)
>> - Execute stop measures via the forked processes on each cpu
>>
>> This should be ideal environment to not interfere with the tested 
>> executable.
>> It would also allow a nicer program structure.
>>
>
> It will be good to capture these ideas in the ToDo file.
>
> Natarajan! WOuld you like to send a patch updating the ToDo file with
> these ideas?


Sure. I can send out a patch capturing these ideas.


-Janak


>
> thanks,
> -- Shuah
>

[PATCHv2 3/3] cpupower: mperf_monitor: Update cpupower to use the RDPRU instruction

[Natarajan, Janakarajan]

AMD Zen 2 introduces the RDPRU instruction which can be used to access some
processor registers which are typically only accessible in privilege level
0. ECX specifies the register to read and EDX:EAX will contain the value read.

ECX: 0 - Register MPERF
     1 - Register APERF

This has the added advantage of not having to use the msr module, since the
userspace to kernel transitions which occur during each read_msr() might
cause APERF and MPERF to go out of sync.

Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
---
 tools/power/cpupower/utils/helpers/cpuid.c    |  4 ++++
 tools/power/cpupower/utils/helpers/helpers.h  |  1 +
 .../utils/idle_monitor/mperf_monitor.c        | 20 +++++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/tools/power/cpupower/utils/helpers/cpuid.c b/tools/power/cpupower/utils/helpers/cpuid.c
index 5cc39d4e23ed..73bfafc60e9b 100644
--- a/tools/power/cpupower/utils/helpers/cpuid.c
+++ b/tools/power/cpupower/utils/helpers/cpuid.c
@@ -131,6 +131,10 @@ int get_cpu_info(struct cpupower_cpu_info *cpu_info)
 		if (ext_cpuid_level >= 0x80000007 &&
 		    (cpuid_edx(0x80000007) & (1 << 9)))
 			cpu_info->caps |= CPUPOWER_CAP_AMD_CBP;
+
+		if (ext_cpuid_level >= 0x80000008 &&
+		    cpuid_ebx(0x80000008) & (1 << 4))
+			cpu_info->caps |= CPUPOWER_CAP_AMD_RDPRU;
 	}
 
 	if (cpu_info->vendor == X86_VENDOR_INTEL) {
diff --git a/tools/power/cpupower/utils/helpers/helpers.h b/tools/power/cpupower/utils/helpers/helpers.h
index 357b19bb136e..c258eeccd05f 100644
--- a/tools/power/cpupower/utils/helpers/helpers.h
+++ b/tools/power/cpupower/utils/helpers/helpers.h
@@ -69,6 +69,7 @@ enum cpupower_cpu_vendor {X86_VENDOR_UNKNOWN = 0, X86_VENDOR_INTEL,
 #define CPUPOWER_CAP_HAS_TURBO_RATIO	0x00000010
 #define CPUPOWER_CAP_IS_SNB		0x00000020
 #define CPUPOWER_CAP_INTEL_IDA		0x00000040
+#define CPUPOWER_CAP_AMD_RDPRU		0x00000080
 
 #define CPUPOWER_AMD_CPBDIS		0x02000000
 
diff --git a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
index afb2e6f8edd3..e7d48cb563c0 100644
--- a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
+++ b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
@@ -19,6 +19,10 @@
 #define MSR_APERF	0xE8
 #define MSR_MPERF	0xE7
 
+#define RDPRU ".byte 0x0f, 0x01, 0xfd"
+#define RDPRU_ECX_MPERF	0
+#define RDPRU_ECX_APERF	1
+
 #define MSR_TSC	0x10
 
 #define MSR_AMD_HWCR 0xc0010015
@@ -89,6 +93,8 @@ static int mperf_get_tsc(unsigned long long *tsc)
 static int get_aperf_mperf(int cpu, unsigned long long *aval,
 				    unsigned long long *mval)
 {
+	unsigned long low_a, high_a;
+	unsigned long low_m, high_m;
 	int ret;
 
 	/*
@@ -101,6 +107,20 @@ static int get_aperf_mperf(int cpu, unsigned long long *aval,
 			return 1;
 	}
 
+	if (cpupower_cpu_info.caps & CPUPOWER_CAP_AMD_RDPRU) {
+		asm volatile(RDPRU
+			     : "=a" (low_a), "=d" (high_a)
+			     : "c" (RDPRU_ECX_APERF));
+		asm volatile(RDPRU
+			     : "=a" (low_m), "=d" (high_m)
+			     : "c" (RDPRU_ECX_MPERF));
+
+		*aval = ((low_a) | (high_a) << 32);
+		*mval = ((low_m) | (high_m) << 32);
+
+		return 0;
+	}
+
 	ret  = read_msr(cpu, MSR_APERF, aval);
 	ret |= read_msr(cpu, MSR_MPERF, mval);
 
-- 
2.17.1

Re: [PATCHv2 0/3] Update cpupower and make it more accurate

[Natarajan, Janakarajan]

On 10/11/2019 2:37 PM, Natarajan, Janakarajan wrote:
> This patchset updates cpupower to make it more accurate by removing
> the userspace to kernel transitions and read_msr initiated IPI delays.
>
> The first patch does a little re-arrangement of variables in the
> cpuidle_monitor struct to prepare for a new flag.
>
> The second patch introduces a per_cpu_schedule flag which, when set,
> will allow cpupower to move to each of the cpus in the system. The
> advantage of this is that the IPI latency is removed when reading
> the APERF/MPERF registers, since an IPI is not generated for rdmsrs
> when the source and destination cpus are the same for the IPI.
>
> The third patch introduces the RDPRU instruction, which will allow
> cpupower to not use the msr module for APERF/MPERF register reads.
> This will remove the userspace to kernel transition delays when
> reading the APERF/MPERF registers.


Any concerns regarding this patchset?


-Janak


>
> v1->v2:
> * Added cover letter.
> * Used bind_cpu instead of rewriting the same code.
> * Moved needs_root to flag sub-struct.
> * Introduced per_cpu_schedule flag.
>
> Janakarajan Natarajan (3):
>    cpupower: Move needs_root variable into a sub-struct
>    cpupower: mperf_monitor: Introduce per_cpu_schedule flag
>    cpupower: mperf_monitor: Update cpupower to use the RDPRU instruction
>
>   tools/power/cpupower/utils/helpers/cpuid.c    |  4 ++
>   tools/power/cpupower/utils/helpers/helpers.h  |  1 +
>   .../utils/idle_monitor/amd_fam14h_idle.c      |  2 +-
>   .../utils/idle_monitor/cpuidle_sysfs.c        |  2 +-
>   .../utils/idle_monitor/cpupower-monitor.c     |  2 +-
>   .../utils/idle_monitor/cpupower-monitor.h     |  5 +-
>   .../utils/idle_monitor/hsw_ext_idle.c         |  2 +-
>   .../utils/idle_monitor/mperf_monitor.c        | 64 +++++++++++++++----
>   .../cpupower/utils/idle_monitor/nhm_idle.c    |  2 +-
>   .../cpupower/utils/idle_monitor/snb_idle.c    |  2 +-
>   10 files changed, 68 insertions(+), 18 deletions(-)
>

Re: [PATCHv2 0/3] Update cpupower and make it more accurate

[Thomas Renninger]

Hi,

Removed: Pu Wen <puwen@hygon.com>

On Tuesday, October 22, 2019 6:39:11 PM CEST Natarajan, Janakarajan wrote:
> On 10/11/2019 2:37 PM, Natarajan, Janakarajan wrote:
> 
> > This patchset updates cpupower to make it more accurate by removing
> > the userspace to kernel transitions and read_msr initiated IPI delays.

Acked-by: Thomas Renninger <trenn@suse.de>

Shuan: If you do not object, it would be great if you can schedule these
to be included into Rafael's pm tree.

It's a nice enhancement for these CPUs.
Doing it even nicer and more generic (per cpu measures) needs further
restructuring, but should not delay this any further.


        Thomas

Re: [PATCHv2 0/3] Update cpupower and make it more accurate

[shuah]

On 10/25/19 4:47 AM, Thomas Renninger wrote:
> Hi,
> 
> Removed: Pu Wen <puwen@hygon.com>
> 
> On Tuesday, October 22, 2019 6:39:11 PM CEST Natarajan, Janakarajan wrote:
>> On 10/11/2019 2:37 PM, Natarajan, Janakarajan wrote:
>>
>>> This patchset updates cpupower to make it more accurate by removing
>>> the userspace to kernel transitions and read_msr initiated IPI delays.
> 
> Acked-by: Thomas Renninger <trenn@suse.de>
> 
> Shuan: If you do not object, it would be great if you can schedule these
> to be included into Rafael's pm tree.
> 

I have no objections.

> It's a nice enhancement for these CPUs.
> Doing it even nicer and more generic (per cpu measures) needs further
> restructuring, but should not delay this any further.
> 

Thanks. I was waiting for you to Ack these before I pulled them in.
I will get them in for 5.5-rc1

thanks,
-- Shuah

Re: [PATCHv2 0/3] Update cpupower and make it more accurate

[shuah]

On 10/25/19 9:18 AM, shuah wrote:
> On 10/25/19 4:47 AM, Thomas Renninger wrote:
>> Hi,
>>
>> Removed: Pu Wen <puwen@hygon.com>
>>
>> On Tuesday, October 22, 2019 6:39:11 PM CEST Natarajan, Janakarajan 
>> wrote:
>>> On 10/11/2019 2:37 PM, Natarajan, Janakarajan wrote:
>>>
>>>> This patchset updates cpupower to make it more accurate by removing
>>>> the userspace to kernel transitions and read_msr initiated IPI delays.
>>
>> Acked-by: Thomas Renninger <trenn@suse.de>
>>
>> Shuan: If you do not object, it would be great if you can schedule these
>> to be included into Rafael's pm tree.
>>
> 
> I have no objections.
> 
>> It's a nice enhancement for these CPUs.
>> Doing it even nicer and more generic (per cpu measures) needs further
>> restructuring, but should not delay this any further.
>>
> 
> Thanks. I was waiting for you to Ack these before I pulled them in.
> I will get them in for 5.5-rc1
> 

Hi Janak,

All your patches fail Signed-off-by check.

WARNING: Missing Signed-off-by: line by nominal patch author 'Natarajan, 
Janakarajan <Janakarajan.Natarajan@amd.com>'

There is a mismatch between your From: and Signed-off-by names? Can you
fix these and resend all 4 patches.

thanks,
-- Shuah

Re: [PATCHv2 0/3] Update cpupower and make it more accurate

[Borislav Petkov]

On Mon, Nov 04, 2019 at 01:21:11PM -0700, shuah wrote:
> WARNING: Missing Signed-off-by: line by nominal patch author 'Natarajan,
> Janakarajan <Janakarajan.Natarajan@amd.com>'
> 
> There is a mismatch between your From: and Signed-off-by names?

That's checkpatch complaining that From: is of the format "Lastname,
Firstname" while the SOB is the other way around. One could use a script
which massages a mail before turning it into patch and fixes up that,
among other things.

-- 
Regards/Gruss,
    Boris.

SUSE Software Solutions Germany GmbH, GF: Felix Imendörffer, HRB 36809, AG Nürnberg