[libvirt] [PATCH 2/2] Alternate CPU affinity impl to cope with NR_CPUS > 1024
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
---
src/util/processinfo.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 84 insertions(+), 0 deletions(-)
diff --git a/src/util/processinfo.c b/src/util/processinfo.c
index aaffd88..a0dac34 100644
--- a/src/util/processinfo.c
+++ b/src/util/processinfo.c
@@ -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;
}
--
1.6.5.2