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cpuplugd: Halt cpu hotplugging on vertical polarization

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On vertical polarization, kernel can be adjusting CPU capacities
dynamically, and cpuplugd can interfere this with hotplug operations
causing performance degradation. To prevent this, check if system has
switched its polarization state, and act accordingly.
If system is on vertical polarization when daemon starts, no CPU hotplug
action is triggered. If system changes to vertical polarization during
daemon runtime, revert cpuhotplug adjustments and stop further CPU
hotplug actions. If system switches back to horizontal polarization
during runtime of the daemon, start evaluating CPU hotplug rules and
trigger adjustments.

Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Mete Durlu <meted@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This commit is contained in:
Mete Durlu
2024-05-23 13:58:08 +02:00
committed by Jan Höppner
parent c91d172c99
commit 147ff1bf49
6 changed files with 111 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files
cpuplugd/main.c
+27 -7
View File
@@ -54,12 +54,12 @@ struct config cfg = {
.hotunplug = NULL,
};
int num_cpu_start, memory, cpu, reload_pending;
long cmm_pagesize_start;
unsigned long meminfo_size, vmstat_size, cpustat_size, varinfo_size;
char *meminfo, *vmstat, *cpustat, *varinfo;
double *timestamps;
unsigned int history_max, history_current, history_prev, sym_names_count;
unsigned long meminfo_size, vmstat_size, cpustat_size, varinfo_size;
int num_cpu_start, memory, cpu, reload_pending, saved_polarization;
char *meminfo, *vmstat, *cpustat, *varinfo;
long cmm_pagesize_start;
double *timestamps;
static struct symbols symbols;
static jmp_buf jmpenv;
@@ -77,8 +77,29 @@ static void eval_cpu_rules(void)
{
double diffs[CPUSTATS], diffs_total, percent_factor;
char *procinfo_current, *procinfo_prev;
int nr_cpus, on_off;
int nr_cpus, on_off, polarization;
polarization = get_polarization();
if (polarization < 0) {
cpuplugd_debug("couldn't determine system polarization\n");
cpuplugd_debug("skipping cpu rule evaluation\n");
return;
}
if (saved_polarization != polarization) {
saved_polarization = polarization;
if (polarization == PLR_VERTICAL) {
/* revert cpu hotplug adjustments after switching from horizontal */
reactivate_cpus();
} else if (polarization == PLR_HORIZONTAL) {
/* reapply cpu config after switching from vertical */
apply_cpu_config();
}
}
if (polarization == PLR_VERTICAL) {
cpuplugd_debug("system is running vertical polarization\n");
cpuplugd_debug("cpuplugd won't make cpu adjustments\n");
return;
}
nr_cpus = get_numcpus();
procinfo_current = cpustat + history_current * cpustat_size;
procinfo_prev = cpustat + history_prev * cpustat_size;
@@ -157,7 +178,6 @@ static void eval_cpu_rules(void)
printf("\n");
printf("---------------------------------------------\n");
}
on_off = 0;
/* Evaluate the hotplug rule */
if (eval_term(cfg.hotplug, &symbols))