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tools/power turbostat: Print /dev/cpu_dma_latency 

Users are puzzled when they use tuned performance and all their
C-states vanish.  Dump /dev/cpu_dma_latency and state
whether the value is default, or constraining,
to explain this situation.

Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Len Brown 2020-05-27 00:38:38 -04:00
parent e00b62f0b0
commit d76bb7a09b
1 changed files with 28 additions and 0 deletions
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28
tools/power/x86/turbostat/turbostat.c
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@ -4698,6 +4698,32 @@ unsigned int intel_model_duplicates(unsigned int model)
}
return model;
}
void print_dev_latency(void)
{
char *path = "/dev/cpu_dma_latency";
int fd;
int value;
int retval;
fd = open(path, O_RDONLY);
if (fd < 0) {
warn("fopen %s\n", path);
return;
}
retval = read(fd, (void *)&value, sizeof(int));
if (retval != sizeof(int)) {
warn("read %s\n", path);
close(fd);
return;
}
fprintf(outf, "/dev/cpu_dma_latency: %d usec (%s)\n",
value, value == 2000000000 ? "default" : "constrained");
close(fd);
}
void process_cpuid()
{
unsigned int eax, ebx, ecx, edx;
@ -4966,6 +4992,8 @@ void process_cpuid()
if (!quiet)
dump_cstate_pstate_config_info(family, model);
if (!quiet)
print_dev_latency();
if (!quiet)
dump_sysfs_cstate_config();
if (!quiet)