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Alternate CPU affinity impl to cope with NR_CPUS > 1024

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The cpu_set_t type can only cope with NR_CPUS <= 1024, beyond this
it is neccessary to use alternate CPU_SET maps with a dynamically
allocated CPU map

* src/util/processinfo.c: Support new unlimited size CPU set type
This commit is contained in:
Daniel P. Berrange 2009-11-16 16:08:29 +00:00
parent 37f415da42
commit a73cd93b24
1 changed files with 84 additions and 0 deletions
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84
src/util/processinfo.c
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@ -38,6 +38,48 @@ int virProcessInfoSetAffinity(pid_t pid,
int maxcpu)
{
int i;
#ifdef CPU_ALLOC
/* New method dynamically allocates cpu mask, allowing unlimted cpus */
int numcpus = 1024;
size_t masklen;
cpu_set_t *mask;
/* Not only may the statically allocated cpu_set_t be too small,
* but there is no way to ask the kernel what size is large enough.
* So you have no option but to pick a size, try, catch EINVAL,
* enlarge, and re-try.
*
* http://lkml.org/lkml/2009/7/28/620
*/
realloc:
masklen = CPU_ALLOC_SIZE(numcpus);
mask = CPU_ALLOC(numcpus);
if (!mask) {
virReportOOMError(NULL);
return -1;
}
CPU_ZERO_S(masklen, mask);
for (i = 0 ; i < maxcpu ; i++) {
if (VIR_CPU_USABLE(map, maplen, 0, i))
CPU_SET_S(i, masklen, mask);
}
if (sched_setaffinity(pid, masklen, mask) < 0) {
CPU_FREE(mask);
if (errno == EINVAL &&
numcpus < (1024 << 8)) { /* 262144 cpus ought to be enough for anyone */
numcpus = numcpus << 2;
goto realloc;
}
virReportSystemError(NULL, errno,
_("cannot set CPU affinity on process %d"), pid);
return -1;
}
CPU_FREE(mask);
#else
/* Legacy method uses a fixed size cpu mask, only allows upto 1024 cpus */
cpu_set_t mask;
CPU_ZERO(&mask);
@ -51,6 +93,7 @@ int virProcessInfoSetAffinity(pid_t pid,
_("cannot set CPU affinity on process %d"), pid);
return -1;
}
#endif
return 0;
}
@ -61,6 +104,46 @@ int virProcessInfoGetAffinity(pid_t pid,
int maxcpu)
{
int i;
#ifdef CPU_ALLOC
/* New method dynamically allocates cpu mask, allowing unlimted cpus */
int numcpus = 1024;
size_t masklen;
cpu_set_t *mask;
/* Not only may the statically allocated cpu_set_t be too small,
* but there is no way to ask the kernel what size is large enough.
* So you have no option but to pick a size, try, catch EINVAL,
* enlarge, and re-try.
*
* http://lkml.org/lkml/2009/7/28/620
*/
realloc:
masklen = CPU_ALLOC_SIZE(numcpus);
mask = CPU_ALLOC(numcpus);
if (!mask) {
virReportOOMError(NULL);
return -1;
}
CPU_ZERO_S(masklen, mask);
if (sched_getaffinity(pid, masklen, mask) < 0) {
CPU_FREE(mask);
if (errno == EINVAL &&
numcpus < (1024 << 8)) { /* 262144 cpus ought to be enough for anyone */
numcpus = numcpus << 2;
goto realloc;
}
virReportSystemError(NULL, errno,
_("cannot set CPU affinity on process %d"), pid);
return -1;
}
for (i = 0 ; i < maxcpu ; i++)
if (CPU_ISSET_S(i, masklen, mask))
VIR_USE_CPU(map, i);
#else
/* Legacy method uses a fixed size cpu mask, only allows upto 1024 cpus */
cpu_set_t mask;
CPU_ZERO(&mask);
@ -73,6 +156,7 @@ int virProcessInfoGetAffinity(pid_t pid,
for (i = 0 ; i < maxcpu ; i++)
if (CPU_ISSET(i, &mask))
VIR_USE_CPU(map, i);
#endif
return 0;
}