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Adjust how we determine if a cpu is online

Browse source 
https://github.com/Irqbalance/irqbalance/issues/159

recently brought to our attention that online cpu status isn't functional on all
arches.  Specifically on parisc, the availability of
/sys/devices/system/cpu/cpu<N>/online is in question.  The implication here is
that its not feasible to accurately determine cpu count, and as a result,
irqbalance doesn't work on that arch

Fix it by changing our online detection strategy.  The file
/sys/devices/system/cpu/online is a cpulist format file that seems to be present
accross all arches and configs.  As such, we can use this file to determine
online status per cpu reliably.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
This commit is contained in:
Neil Horman 2020-08-27 10:11:04 -04:00
parent 8df73e4c2a
commit b3f95beb62
1 changed files with 11 additions and 4 deletions
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15
cputree.c
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@ -263,6 +263,7 @@ static void do_one_cpu(char *path)
{
struct topo_obj *cpu;
char new_path[PATH_MAX];
char *online_path ="/sys/devices/system/cpu/online";
cpumask_t cache_mask, package_mask;
struct topo_obj *cache;
DIR *dir;
@ -270,12 +271,18 @@ static void do_one_cpu(char *path)
int nodeid;
int packageid = 0;
unsigned int max_cache_index, cache_index, cache_stat;
int online_status = 1;
cpumask_t online_cpus;
char *cpunrptr = NULL;
int cpunr = -1;
/* skip offline cpus */
snprintf(new_path, ADJ_SIZE(path,"/online"), "%s/online", path);
process_one_line(new_path, get_int, &online_status);
if (!online_status)
cpus_clear(online_cpus);
process_one_line(online_path, get_mask_from_cpulist, &online_cpus);
/* Get the current cpu number from the path */
cpunrptr = rindex(path, '/');
cpunrptr += 4;
cpunr = atoi(cpunrptr);
if (!cpu_isset(cpunr, online_cpus))
return;
cpu = calloc(1, sizeof(struct topo_obj));