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eal/linux: fix numa node detection

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Using the "physical_package_id" as a fallback for determining the
numa node of a core tends to be unreliable. Fix this by using a
detection routine which reads the numa information from
/sys/devices/system/node and just returns a numa node of 0 on
failure.

Reported-by: Wang Sheng-Hui <shhuiw@gmail.com>
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
This commit is contained in:
Bruce Richardson 2015-04-22 14:31:55 +01:00 committed by Thomas Monjalon
parent bd785f6f67
commit 94ef296414
1 changed files with 14 additions and 46 deletions
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60
lib/librte_eal/linuxapp/eal/eal_lcore.c
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@ -49,7 +49,7 @@
#define SYS_CPU_DIR "/sys/devices/system/cpu/cpu%u"
#define CORE_ID_FILE "topology/core_id"
#define PHYS_PKG_FILE "topology/physical_package_id"
#define NUMA_NODE_PATH "/sys/devices/system/node"
/* Check if a cpu is present by the presence of the cpu information for it */
static int
@ -66,58 +66,26 @@ cpu_detected(unsigned lcore_id)
return 1;
}
/* Get CPU socket id (NUMA node) by reading directory
* /sys/devices/system/cpu/cpuX looking for symlink "nodeY"
* which gives the NUMA topology information.
* Note: physical package id != NUMA node, but we use it as a
* fallback for kernels which don't create a nodeY link
/*
* Get CPU socket id (NUMA node) for a logical core.
*
* This searches each nodeX directories in /sys for the symlink for the given
* lcore_id and returns the numa node where the lcore is found. If lcore is not
* found on any numa node, returns zero.
*/
unsigned
eal_cpu_socket_id(unsigned lcore_id)
{
const char node_prefix[] = "node";
const size_t prefix_len = sizeof(node_prefix) - 1;
char path[PATH_MAX];
DIR *d = NULL;
unsigned long id = 0;
struct dirent *e;
char *endptr = NULL;
unsigned socket;
int len = snprintf(path, sizeof(path),
SYS_CPU_DIR, lcore_id);
if (len <= 0 || (unsigned)len >= sizeof(path))
goto err;
for (socket = 0; socket < RTE_MAX_NUMA_NODES; socket++) {
char path[PATH_MAX];
d = opendir(path);
if (!d)
goto err;
while ((e = readdir(d)) != NULL) {
if (strncmp(e->d_name, node_prefix, prefix_len) == 0) {
id = strtoul(e->d_name+prefix_len, &endptr, 0);
break;
}
snprintf(path, sizeof(path), "%s/node%u/cpu%u", NUMA_NODE_PATH,
socket, lcore_id);
if (access(path, F_OK) == 0)
return socket;
}
if (endptr == NULL || *endptr!='\0' || endptr == e->d_name+prefix_len) {
RTE_LOG(WARNING, EAL, "Cannot read numa node link "
"for lcore %u - using physical package id instead\n",
lcore_id);
len = snprintf(path, sizeof(path), SYS_CPU_DIR "/%s",
lcore_id, PHYS_PKG_FILE);
if (len <= 0 || (unsigned)len >= sizeof(path))
goto err;
if (eal_parse_sysfs_value(path, &id) != 0)
goto err;
}
closedir(d);
return (unsigned)id;
err:
if (d)
closedir(d);
RTE_LOG(ERR, EAL, "Error getting NUMA socket information from %s "
"for lcore %u - assuming NUMA socket 0\n", SYS_CPU_DIR, lcore_id);
return 0;
}