Re: [PATCH v2] cpupower: fix TSC MHz calculation for Mperf monitor

From: Shuah Khan
Date: Wed Dec 11 2024 - 15:54:48 EST


On 12/10/24 20:20, He Rongguang wrote:
From e17f252433c923578e9c386a998200e488d9567d Mon Sep 17 00:00:00 2001
From: He Rongguang <herongguang@xxxxxxxxxxxxxxxxx>
Date: Thu, 28 Nov 2024 16:50:05 +0800
Subject: [PATCH] cpupower: fix TSC MHz calculation

Commit 'cpupower: Make TSC read per CPU for Mperf monitor' (c2adb1877b7)
changes TSC counter reads per cpu, but left time diff global (from start
of all cpus to end of all cpus), thus diff(time) is too large for a
cpu's tsc counting, resulting in far less than acutal TSC_Mhz and thus
`cpupower monitor` showing far less than actual cpu realtime frequency.

/proc/cpuinfo shows frequency:
cat /proc/cpuinfo | egrep -e 'processor' -e 'MHz'
...
processor : 171
cpu MHz : 4108.498
...

before fix (System 100% busy):
| Mperf || Idle_Stats
CPU| C0 | Cx | Freq || POLL | C1 | C2
171| 0.77| 99.23| 2279|| 0.00| 0.00| 0.00

after fix (System 100% busy):
| Mperf || Idle_Stats
CPU| C0 | Cx | Freq || POLL | C1 | C2
171| 0.46| 99.54| 4095|| 0.00| 0.00| 0.00

Fixes: c2adb1877b76 ("cpupower: Make TSC read per CPU for Mperf monitor")
Signed-off-by: He Rongguang <herongguang@xxxxxxxxxxxxxxxxx>
---
Changes in v2:
- Fix scripts/checkpatch.pl style warnings.
- Link to v1:
https://lore.kernel.org/linux-pm/269b8bb2-85b5-4cc9-9354-a1270f2eed35@xxxxxxxxxxxxxxxxx/T/#u
---

Are you sure you sent me the right patch. I am seeing exact
same errors. How are you sending your patches.

Here are the problems I am seeing:

ERROR: patch seems to be corrupt (line wrapped?)
#103: FILE: :173:
double *percent,

WARNING: It's generally not useful to have the filename in the file
#108: FILE: :177:
+ timediff = max_frequency * timespec_diff_us(time_start[cpu],

WARNING: It's generally not useful to have the filename in the file
#119: FILE: :210:
+ time_diff = timespec_diff_us(time_start[cpu], time_end[cpu]);

WARNING: It's generally not useful to have the filename in the file
#130: FILE: :230:
+ clock_gettime(CLOCK_REALTIME, &time_start[cpu]);

WARNING: It's generally not useful to have the filename in the file
#138: FILE: :245:
+ clock_gettime(CLOCK_REALTIME, &time_end[cpu]);

WARNING: It's generally not useful to have the filename in the file
#149: FILE: :351:
+ time_start = calloc(cpu_count, sizeof(struct timespec));

WARNING: It's generally not useful to have the filename in the file
#150: FILE: :352:
+ time_end = calloc(cpu_count, sizeof(struct timespec));

WARNING: It's generally not useful to have the filename in the file
#158: FILE: :365:
+ free(time_start);

WARNING: It's generally not useful to have the filename in the file
#159: FILE: :366:
+ free(time_end);

thanks,
-- Shuah