From: David Marchand <david.march...@6wind.com>
Relying on /proc/cpuinfo to count the number of available cores is not
the best option:
- The code is x86-specific.
- If the process is started with a different CPU affinity, then it will
wrongly try to start too many threads (for an example, imagine an OVS
daemon restricted to 4 CPU threads on a 128 threads system).
This commit removes /proc/cpuinfo parsing, and introduces instead a call
to sched_getaffinity(), which is architecture-independant, in order to
retrieve the list of CPU threads available to the current process and to
count them.
Signed-off-by: David Marchand <david.march...@6wind.com>
Signed-off-by: Liu Xiaofeng <xiaofeng....@6wind.com>
Signed-off-by: Quentin Monnet <quentin.mon...@6wind.com>
---
v2:
Add `CPU_FREE(set);`
Tests: on a VM with 3 cores:
- OVS master:
# taskset -c 1 ovs-vswitchd --pidfile
2016-06-02T11:05:47Z|00001|ovs_numa|INFO|Discovered 3 CPU cores on NUMA node 0
2016-06-02T11:05:47Z|00002|ovs_numa|INFO|Discovered 1 NUMA nodes and 3 CPU cores
[…]
2016-06-02T11:05:57Z|00019|memory|INFO|5072 kB peak resident set size after
10.0 seconds
2016-06-02T11:05:57Z|00020|memory|INFO|handlers:2 ports:2 revalidators:1
rules:5 udpif keys:1
- OVS with patch:
# taskset -c 1 ovs-vswitchd --pidfile
2016-06-02T11:10:12Z|00001|ovs_numa|INFO|Discovered 3 CPU cores on NUMA node 0
2016-06-02T11:10:12Z|00002|ovs_numa|INFO|Discovered 1 NUMA nodes and 3 CPU cores
[…]
2016-06-02T11:10:22Z|00019|memory|INFO|5052 kB peak resident set size after
10.0 seconds
2016-06-02T11:10:22Z|00020|memory|INFO|handlers:1 ports:2 revalidators:1 rules:5
lib/ovs-thread.c | 77 +++++++++++---------------------------------------------
1 file changed, 14 insertions(+), 63 deletions(-)
diff --git a/lib/ovs-thread.c b/lib/ovs-thread.c
index 6e6345273c7c..aedd391936f5 100644
--- a/lib/ovs-thread.c
+++ b/lib/ovs-thread.c
@@ -547,67 +547,8 @@ ovs_thread_stats_next_bucket(const struct ovsthread_stats
*stats, size_t i)
}
-/* Parses /proc/cpuinfo for the total number of physical cores on this system
- * across all CPU packages, not counting hyper-threads.
- *
- * Sets *n_cores to the total number of cores on this system, or 0 if the
- * number cannot be determined. */
-static void
-parse_cpuinfo(long int *n_cores)
-{
- static const char file_name[] = "/proc/cpuinfo";
- char line[128];
- uint64_t cpu = 0; /* Support up to 64 CPU packages on a single system. */
- long int cores = 0;
- FILE *stream;
-
- stream = fopen(file_name, "r");
- if (!stream) {
- VLOG_DBG("%s: open failed (%s)", file_name, ovs_strerror(errno));
- return;
- }
-
- while (fgets(line, sizeof line, stream)) {
- unsigned int id;
-
- /* Find the next CPU package. */
- if (ovs_scan(line, "physical id%*[^:]: %u", &id)) {
- if (id > 63) {
- VLOG_WARN("Counted over 64 CPU packages on this system. "
- "Parsing %s for core count may be inaccurate.",
- file_name);
- cores = 0;
- break;
- }
-
- if (cpu & (1ULL << id)) {
- /* We've already counted this package's cores. */
- continue;
- }
- cpu |= 1ULL << id;
-
- /* Find the number of cores for this package. */
- while (fgets(line, sizeof line, stream)) {
- int count;
-
- if (ovs_scan(line, "cpu cores%*[^:]: %u", &count)) {
- cores += count;
- break;
- }
- }
- }
- }
- fclose(stream);
-
- *n_cores = cores;
-}
-
-/* Returns the total number of cores on this system, or 0 if the number cannot
- * be determined.
- *
- * Tries not to count hyper-threads, but may be inaccurate - particularly on
- * platforms that do not provide /proc/cpuinfo, but also if /proc/cpuinfo is
- * formatted different to the layout that parse_cpuinfo() expects. */
+/* Returns the total number of cores available to this process, or 0 if the
+ * number cannot be determined. */
int
count_cpu_cores(void)
{
@@ -616,9 +557,19 @@ count_cpu_cores(void)
if (ovsthread_once_start(&once)) {
#ifndef _WIN32
- parse_cpuinfo(&n_cores);
- if (!n_cores) {
- n_cores = sysconf(_SC_NPROCESSORS_ONLN);
+ n_cores = sysconf(_SC_NPROCESSORS_ONLN);
+ if (n_cores > 0) {
+ cpu_set_t *set = CPU_ALLOC(n_cores);
+
+ if (set) {
+ size_t size = CPU_ALLOC_SIZE(n_cores);
+
+ if (!sched_getaffinity(0, size, set)) {
+ n_cores = CPU_COUNT_S(size, set);
+ }
+ }
+
+ CPU_FREE(set);
}
#else
SYSTEM_INFO sysinfo;
--
2.1.4
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