LinuxLists.cc - [PATCH 0/2] turbostat, support CPU0 hotplug

2015-05-22 12:01:13

Subject: [PATCH 0/2] turbostat, support CPU0 hotplug

2015-05-22 12:01:53

Subject: [PATCH 1/2] turbostat, add base_cpu

turbostat does not function properly on systems that support CPU0 hotplug.
When running turbostat on these systems the following error is seen.

[root@intel-chiefriver-04 ~]# turbostat ls
turbostat: no /dev/cpu/0/msr
Try "# modprobe msr": No such file or directory

This happens because /dev/cpu/0 is hardcoded in several locations in the
turbostat code.

This patch adds base_cpu, which will be used to track the lowest cpu number
on the system. This patch does not add any functionality differences and
sets base_cpu to 0.

Signed-off-by: Prarit Bhargava <[email protected]>
---
tools/power/x86/turbostat/turbostat.c | 31 ++++++++++++++++++-------------
1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index bac98ca..8c2e761 100644
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -91,6 +91,7 @@ unsigned int do_gfx_perf_limit_reasons;
unsigned int do_ring_perf_limit_reasons;
unsigned int crystal_hz;
unsigned long long tsc_hz;
+int base_cpu = 0;

#define RAPL_PKG (1 << 0)
/* 0x610 MSR_PKG_POWER_LIMIT */
@@ -1150,7 +1151,7 @@ dump_nhm_platform_info(void)
unsigned long long msr;
unsigned int ratio;

- get_msr(0, MSR_NHM_PLATFORM_INFO, &msr);
+ get_msr(base_cpu, MSR_NHM_PLATFORM_INFO, &msr);

fprintf(stderr, "cpu0: MSR_NHM_PLATFORM_INFO: 0x%08llx\n", msr);

@@ -1162,7 +1163,7 @@ dump_nhm_platform_info(void)
fprintf(stderr, "%d * %.0f = %.0f MHz base frequency\n",
ratio, bclk, ratio * bclk);

- get_msr(0, MSR_IA32_POWER_CTL, &msr);
+ get_msr(base_cpu, MSR_IA32_POWER_CTL, &msr);
fprintf(stderr, "cpu0: MSR_IA32_POWER_CTL: 0x%08llx (C1E auto-promotion: %sabled)\n",
msr, msr & 0x2 ? "EN" : "DIS");

@@ -1175,7 +1176,7 @@ dump_hsw_turbo_ratio_limits(void)
unsigned long long msr;
unsigned int ratio;

- get_msr(0, MSR_TURBO_RATIO_LIMIT2, &msr);
+ get_msr(base_cpu, MSR_TURBO_RATIO_LIMIT2, &msr);

fprintf(stderr, "cpu0: MSR_TURBO_RATIO_LIMIT2: 0x%08llx\n", msr);

@@ -1197,7 +1198,7 @@ dump_ivt_turbo_ratio_limits(void)
unsigned long long msr;
unsigned int ratio;

- get_msr(0, MSR_TURBO_RATIO_LIMIT1, &msr);
+ get_msr(base_cpu, MSR_TURBO_RATIO_LIMIT1, &msr);

fprintf(stderr, "cpu0: MSR_TURBO_RATIO_LIMIT1: 0x%08llx\n", msr);

@@ -1249,7 +1250,7 @@ dump_nhm_turbo_ratio_limits(void)
unsigned long long msr;
unsigned int ratio;

- get_msr(0, MSR_TURBO_RATIO_LIMIT, &msr);
+ get_msr(base_cpu, MSR_TURBO_RATIO_LIMIT, &msr);

fprintf(stderr, "cpu0: MSR_TURBO_RATIO_LIMIT: 0x%08llx\n", msr);

@@ -1300,7 +1301,7 @@ dump_nhm_cst_cfg(void)
{
unsigned long long msr;

- get_msr(0, MSR_NHM_SNB_PKG_CST_CFG_CTL, &msr);
+ get_msr(base_cpu, MSR_NHM_SNB_PKG_CST_CFG_CTL, &msr);

#define SNB_C1_AUTO_UNDEMOTE (1UL << 27)
#define SNB_C3_AUTO_UNDEMOTE (1UL << 28)
@@ -1594,8 +1595,10 @@ restart:
void check_dev_msr()
{
struct stat sb;
+ char pathname[32];

- if (stat("/dev/cpu/0/msr", &sb))
+ sprintf(pathname, "/dev/cpu/%d/msr", base_cpu);
+ if (stat(pathname, &sb))
if (system("/sbin/modprobe msr > /dev/null 2>&1"))
err(-5, "no /dev/cpu/0/msr, Try \"# modprobe msr\" ");
}
@@ -1608,6 +1611,7 @@ void check_permissions()
cap_user_data_t cap_data = &cap_data_data;
extern int capget(cap_user_header_t hdrp, cap_user_data_t datap);
int do_exit = 0;
+ char pathname[32];

/* check for CAP_SYS_RAWIO */
cap_header->pid = getpid();
@@ -1622,7 +1626,8 @@ void check_permissions()
}

/* test file permissions */
- if (euidaccess("/dev/cpu/0/msr", R_OK)) {
+ sprintf(pathname, "/dev/cpu/%d/msr", base_cpu);
+ if (euidaccess(pathname, R_OK)) {
do_exit++;
warn("/dev/cpu/0/msr open failed, try chown or chmod +r /dev/cpu/*/msr");
}
@@ -1704,7 +1709,7 @@ int probe_nhm_msrs(unsigned int family, unsigned int model)
default:
return 0;
}
- get_msr(0, MSR_NHM_SNB_PKG_CST_CFG_CTL, &msr);
+ get_msr(base_cpu, MSR_NHM_SNB_PKG_CST_CFG_CTL, &msr);

pkg_cstate_limit = pkg_cstate_limits[msr & 0xF];

@@ -1925,7 +1930,7 @@ double get_tdp(model)
unsigned long long msr;

if (do_rapl & RAPL_PKG_POWER_INFO)
- if (!get_msr(0, MSR_PKG_POWER_INFO, &msr))
+ if (!get_msr(base_cpu, MSR_PKG_POWER_INFO, &msr))
return ((msr >> 0) & RAPL_POWER_GRANULARITY) * rapl_power_units;

switch (model) {
@@ -2006,7 +2011,7 @@ void rapl_probe(unsigned int family, unsigned int model)
}

/* units on package 0, verify later other packages match */
- if (get_msr(0, MSR_RAPL_POWER_UNIT, &msr))
+ if (get_msr(base_cpu, MSR_RAPL_POWER_UNIT, &msr))
return;

rapl_power_units = 1.0 / (1 << (msr & 0xF));
@@ -2340,7 +2345,7 @@ double slm_bclk(void)
unsigned int i;
double freq;

- if (get_msr(0, MSR_FSB_FREQ, &msr))
+ if (get_msr(base_cpu, MSR_FSB_FREQ, &msr))
fprintf(stderr, "SLM BCLK: unknown\n");

i = msr & 0xf;
@@ -2408,7 +2413,7 @@ int set_temperature_target(struct thread_data *t, struct core_data *c, struct pk
if (!do_nhm_platform_info)
goto guess;

- if (get_msr(0, MSR_IA32_TEMPERATURE_TARGET, &msr))
+ if (get_msr(base_cpu, MSR_IA32_TEMPERATURE_TARGET, &msr))
goto guess;

target_c_local = (msr >> 16) & 0xFF;
--
1.8.3.1

2015-05-22 12:01:35

by Prarit Bhargava

[permalink] [raw]

Subject: [PATCH 2/2] turbostat, add set_base_cpu()

2015-05-22 15:55:22

by Brown, Len

[permalink] [raw]

Subject: RE: [PATCH 2/2] turbostat, add set_base_cpu()

> +void set_base_cpu(void)
> +{
> + int cpu;
> +
> + for (cpu = 0; cpu <= topo.max_cpu_num; ++cpu) {
> + if (cpu_is_not_present(cpu))
> + continue;
> + base_cpu = cpu;
> + break;
> + }
> +
> + if (base_cpu == -1)
> + err(-ENODEV, "No valid cpus found");
> +}

cpu0 hard-coding is indeed arbitrary.
However, so is this proposed replacement, base_cpu.
Either may not match where turbostat is currently running,
and thus could provoke unnecessary cross-calls to get there.

I think it would be better to ask getcpu(2) where we are already running,
and simply use that one. I think we can call it once and cache it,
as you proposed, rather than multiple system calls.

thanks,
-Len

ps. patches to turbostat should go to [email protected]

2015-05-22 21:44:55

by Prarit Bhargava

[permalink] [raw]

Subject: Re: [PATCH 2/2] turbostat, add set_base_cpu()

On 05/22/2015 11:55 AM, Brown, Len wrote:
>> +void set_base_cpu(void)
>> +{
>> + int cpu;
>> +
>> + for (cpu = 0; cpu <= topo.max_cpu_num; ++cpu) {
>> + if (cpu_is_not_present(cpu))
>> + continue;
>> + base_cpu = cpu;
>> + break;
>> + }
>> +
>> + if (base_cpu == -1)
>> + err(-ENODEV, "No valid cpus found");
>> +}
>
>
> cpu0 hard-coding is indeed arbitrary.
> However, so is this proposed replacement, base_cpu.
> Either may not match where turbostat is currently running,
> and thus could provoke unnecessary cross-calls to get there.
>
> I think it would be better to ask getcpu(2) where we are already running,
> and simply use that one. I think we can call it once and cache it,
> as you proposed, rather than multiple system calls.
>

Okay, will do that in a v2.

P.

> thanks,
> -Len
>
> ps. patches to turbostat should go to [email protected]

Oh -- I ran get_maintainer.pl on this patchset and linux-pm didn't show up.
I'll send a patch to fix that...

P.

>
>

2015-05-22 22:30:22

by Prarit Bhargava

[permalink] [raw]

Subject: Re: [PATCH 2/2] turbostat, add set_base_cpu()

On 05/22/2015 11:55 AM, Brown, Len wrote:
>> +void set_base_cpu(void)
>> +{
>> + int cpu;
>> +
>> + for (cpu = 0; cpu <= topo.max_cpu_num; ++cpu) {
>> + if (cpu_is_not_present(cpu))
>> + continue;
>> + base_cpu = cpu;
>> + break;
>> + }
>> +
>> + if (base_cpu == -1)
>> + err(-ENODEV, "No valid cpus found");
>> +}
>
>
> cpu0 hard-coding is indeed arbitrary.
> However, so is this proposed replacement, base_cpu.
> Either may not match where turbostat is currently running,
> and thus could provoke unnecessary cross-calls to get there.
>
> I think it would be better to ask getcpu(2) where we are already running,
> and simply use that one. I think we can call it once and cache it,
> as you proposed, rather than multiple system calls.

Any objection to sched_getcpu()? That way the code is simply

base_cpu = sched_getcpu();

if (base_cpu == -1)
err(-ENODEV, "No valid cpus found");

P.

>
> thanks,
> -Len
>
> ps. patches to turbostat should go to [email protected]
>
>

2015-05-26 00:32:44

by Brown, Len

[permalink] [raw]

Subject: RE: [PATCH 2/2] turbostat, add set_base_cpu()

> -----Original Message-----
> From: Prarit Bhargava [mailto:[email protected]]
> Sent: Friday, May 22, 2015 6:30 PM
> To: Brown, Len
> Cc: [email protected]; [email protected]; Semin, Andrey
> Subject: Re: [PATCH 2/2] turbostat, add set_base_cpu()
>
>
>
> On 05/22/2015 11:55 AM, Brown, Len wrote:
> >> +void set_base_cpu(void)
> >> +{
> >> + int cpu;
> >> +
> >> + for (cpu = 0; cpu <= topo.max_cpu_num; ++cpu) {
> >> + if (cpu_is_not_present(cpu))
> >> + continue;
> >> + base_cpu = cpu;
> >> + break;
> >> + }
> >> +
> >> + if (base_cpu == -1)
> >> + err(-ENODEV, "No valid cpus found");
> >> +}
> >
> >
> > cpu0 hard-coding is indeed arbitrary.
> > However, so is this proposed replacement, base_cpu.
> > Either may not match where turbostat is currently running,
> > and thus could provoke unnecessary cross-calls to get there.
> >
> > I think it would be better to ask getcpu(2) where we are already
> running,
> > and simply use that one. I think we can call it once and cache it,
> > as you proposed, rather than multiple system calls.
>
> Any objection to sched_getcpu()? That way the code is simply
>
> base_cpu = sched_getcpu();
>
> if (base_cpu == -1)
> err(-ENODEV, "No valid cpus found");

Agreed, that is better than invoking the syscall directly,
as we already are using the sched.h interface in this code.

thanks,
-Len