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Issue eclipse-omr#173 Rewrite NUMA CPU affinity parsing code for speed
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Use the "cpumap" file if possible instead of parsing every entry in the
"node" directory. Fall back to parsing the directory entries if cpumap doesn't work.

Signed-off-by: Peter Bain <[email protected]>
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@pdbain-ibm
pdbain-ibm committed Sep 16, 2016
1 parent da9e610 commit e764ec7
Showing 1 changed file with 117 additions and 24 deletions.
141 changes: 117 additions & 24 deletions thread/linux/omrthreadnuma.c
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Original file line number Diff line number Diff line change
Expand Up @@ -23,16 +23,23 @@
*/
/* _GNU_SOURCE must be defined for CPU_SETSIZE */
#define _GNU_SOURCE
#include <ctype.h>
#include <dirent.h>
#include <fcntl.h>
#include <inttypes.h>
#include <sched.h>
#include <sys/stat.h>
#include <stdio.h>

#include "omrcfg.h"
#include "threaddef.h"

static uintptr_t cpuset_subset_or_equal(cpu_set_t *subset, cpu_set_t *superset);
static void cpuset_logical_or(cpu_set_t *destination, const cpu_set_t *source);

#undef OMR_VERBOSE_NUMA_NODE_DATA
#ifdef OMR_VERBOSE_NUMA_NODE_DATA
void dumpNumaInfo();
#endif
static BOOLEAN isNumaAvailable = FALSE;
static uintptr_t numNodes = 0;
static cpu_set_t defaultAffinityMask = {{0}};
Expand Down Expand Up @@ -134,42 +141,104 @@ initializeNumaNodeData(omrthread_library_t threadLibrary, uintptr_t numNodes)
} else {
DIR *nodes = NULL;
unsigned long nodeIndex = 0;
const char NODE_PATH[] = "/sys/devices/system/node/";
for (nodeIndex = 0; nodeIndex <= numNodes; nodeIndex++) {
CPU_ZERO(&numaNodeData[nodeIndex].cpu_set);
numaNodeData[nodeIndex].cpu_count = 0;
}

nodes = opendir("/sys/devices/system/node/");
nodes = opendir(NODE_PATH);
if (NULL == nodes) {
result = -1;
} else {
struct dirent *node = readdir(nodes);
while (NULL != node) {
if (1 == sscanf(node->d_name, "node%lu", &nodeIndex)) {
if (nodeIndex < numNodes) {
DIR *cpus = NULL;
char nodeName[sizeof("/sys/devices/system/node/") + NAME_MAX + 1] = "/sys/devices/system/node/";
strcat(nodeName, node->d_name);
cpus = opendir(nodeName);
if (NULL != cpus) {
struct dirent *cpu = readdir(cpus);
while (NULL != cpu) {
unsigned long cpuIndex = 0;
if (1 == sscanf(cpu->d_name, "cpu%lu", &cpuIndex)) {
CPU_SET(cpuIndex, &numaNodeData[nodeIndex + 1].cpu_set);
numaNodeData[nodeIndex + 1].cpu_count += 1;

/* add all cpus to the synthetic 0 node */
CPU_SET(cpuIndex, &numaNodeData[0].cpu_set);
numaNodeData[0].cpu_count += 1;
if (NULL != node) {
const char CPUMAP[] = "/cpumap";
char pathBuffer[sizeof(NODE_PATH) + sizeof(CPUMAP) + 16]; /* extra space for "node<n>" & terminating null */
strcpy(pathBuffer, NODE_PATH);
char *nodeRoot = pathBuffer + sizeof(NODE_PATH) - 1; /* shortcut to the end of the string */
do {
if (1 == sscanf(node->d_name, "node%lu", &nodeIndex)) {
if (nodeIndex < numNodes) {
strcpy(nodeRoot, node->d_name);
strcat(nodeRoot, CPUMAP);
int cpumapFile = open(pathBuffer, O_RDONLY);
BOOLEAN cpumapOkay = FALSE;
if (-1 != cpumapFile) {
char defaultMapBuffer[128];
char * mapBuffer = defaultMapBuffer;
size_t bufferSize = sizeof(defaultMapBuffer);
size_t bytesRead = read(cpumapFile, mapBuffer, bufferSize);
if (bytesRead == bufferSize) { /* buffer possibly not big enough */
bufferSize = 4096;
mapBuffer = malloc(bufferSize);
if (NULL == mapBuffer) {
result = -1;
close(cpumapFile);
break;
}
size_t bytesRead = read(cpumapFile, mapBuffer, bufferSize-1);
mapBuffer[bytesRead] = '\0';
}
if ((0 != bytesRead) && (bytesRead < bufferSize-1)) { /* the buffer was too small */
/* scan from the end of the line (lowest numbered CPU) toward the front */
char *cursor = mapBuffer+strlen(mapBuffer);
uint32_t charCount = 0;
do {
while ((cursor > mapBuffer) && !isxdigit(*cursor)) { /* find the start of the hex string */
cursor -= 1;
}
uint32_t cpuIndex = 4 * charCount; /* each hex digit represents 4 CPUs. Use the count from the last iteration */
while ((cursor > mapBuffer) && isxdigit(*cursor)) {
charCount += 1;
cursor -= 1;
}
uintmax_t cpuMap = strtoumax((cursor == mapBuffer)? cursor: cursor + 1, NULL, 16);
/* cursor points to a non-hex char if not at the front of the buffer */
while ((0 != cpuMap)) {
if (0 != (cpuMap & 1)) {
CPU_SET(cpuIndex, &numaNodeData[nodeIndex + 1].cpu_set);
numaNodeData[nodeIndex + 1].cpu_count += 1;

/* add all cpus to the synthetic 0 node */
CPU_SET(cpuIndex, &numaNodeData[0].cpu_set);
numaNodeData[0].cpu_count += 1;
}
cpuMap >>= 1;
cpuIndex += 1;
}
} while (cursor > mapBuffer);
}
if (mapBuffer != defaultMapBuffer) {
free(mapBuffer);
}
close(cpumapFile);
cpumapOkay = TRUE;
}
if (!cpumapOkay) { /* read the directory entries */
strcpy(nodeRoot, node->d_name); /* strip off "/cpulist". Updates pathBuffer */
DIR *cpus = opendir(pathBuffer);
if (NULL != cpus) {
struct dirent *cpu = readdir(cpus);
while (NULL != cpu) {
unsigned long cpuIndex = 0;
if (1 == sscanf(cpu->d_name, "cpu%lu", &cpuIndex)) {
CPU_SET(cpuIndex, &numaNodeData[nodeIndex + 1].cpu_set);
numaNodeData[nodeIndex + 1].cpu_count += 1;

/* add all cpus to the synthetic 0 node */
CPU_SET(cpuIndex, &numaNodeData[0].cpu_set);
numaNodeData[0].cpu_count += 1;
}
cpu = readdir(cpus);
}
closedir(cpus);
}
cpu = readdir(cpus);
}
closedir(cpus);
}
}
}
node = readdir(nodes);
node = readdir(nodes);
} while (NULL != node);
}
closedir(nodes);
}
Expand All @@ -196,6 +265,9 @@ omrthread_numa_init(omrthread_library_t threadLibrary)
if (0 == initializeNumaNodeData(threadLibrary, numNodes)) {
isNumaAvailable = TRUE;
}
#ifdef OMR_VERBOSE_NUMA_NODE_DATA
dumpNumaInfo();
#endif
}
/* find our current affinity mask since we will need it when removing any affinity binding from threads, later (since we still want to honour restrictions we inherited from the environment) */
CPU_ZERO(&defaultAffinityMask);
Expand Down Expand Up @@ -434,3 +506,24 @@ omrthread_numa_get_node_affinity(omrthread_t thread, uintptr_t *numaNodes, uintp
*nodeCount = nodesSoFar;
return result;
}

#ifdef OMR_VERBOSE_NUMA_NODE_DATA
void
dumpNumaInfo() {
uintptr_t numaMaxNode = omrthread_numa_get_max_node();
uint32_t node = 0;

for (node = 0; node <= numaMaxNode; node++) {
uint32_t i = 0;
printf("Node %d cpus:", node);
cpu_set_t *numaNodeCPUs = &numaNodeData[node].cpu_set;
for (i = 0; i < CPU_SETSIZE; i++) {
if (CPU_ISSET(i, numaNodeCPUs)) {
printf(" %d ", i);
}
}
printf("\n");
}

}
#endif

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