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8148987: [Linux] Allow building on older systems without CPU_ALLOC support

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Reviewed-by: dsamersoff, stuefe, dcubed
This commit is contained in:
David Holmes 2016-02-10 22:22:48 -05:00
parent 8d71b5adce
commit e82f5cf677
1 changed files with 32 additions and 2 deletions
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34
hotspot/src/os/linux/vm/os_linux.cpp
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@ -4771,6 +4771,25 @@ void os::make_polling_page_readable(void) {
}
}
// older glibc versions don't have this macro (which expands to
// an optimized bit-counting function) so we have to roll our own
#ifndef CPU_COUNT
static int _cpu_count(const cpu_set_t* cpus) {
int count = 0;
// only look up to the number of configured processors
for (int i = 0; i < os::processor_count(); i++) {
if (CPU_ISSET(i, cpus)) {
count++;
}
}
return count;
}
#define CPU_COUNT(cpus) _cpu_count(cpus)
#endif // CPU_COUNT
// Get the current number of available processors for this process.
// This value can change at any time during a process's lifetime.
// sched_getaffinity gives an accurate answer as it accounts for cpusets.
@ -4786,6 +4805,9 @@ int os::active_processor_count() {
int configured_cpus = processor_count(); // upper bound on available cpus
int cpu_count = 0;
// old build platforms may not support dynamic cpu sets
#ifdef CPU_ALLOC
// To enable easy testing of the dynamic path on different platforms we
// introduce a diagnostic flag: UseCpuAllocPath
if (configured_cpus >= CPU_SETSIZE || UseCpuAllocPath) {
@ -4814,10 +4836,18 @@ int os::active_processor_count() {
log_trace(os)("active_processor_count: using static path - configured processors: %d",
configured_cpus);
}
#else // CPU_ALLOC
// these stubs won't be executed
#define CPU_COUNT_S(size, cpus) -1
#define CPU_FREE(cpus)
log_trace(os)("active_processor_count: only static path available - configured processors: %d",
configured_cpus);
#endif // CPU_ALLOC
// pid 0 means the current thread - which we have to assume represents the process
if (sched_getaffinity(0, cpus_size, cpus_p) == 0) {
if (cpus_p != &cpus) {
if (cpus_p != &cpus) { // can only be true when CPU_ALLOC used
cpu_count = CPU_COUNT_S(cpus_size, cpus_p);
}
else {
@ -4831,7 +4861,7 @@ int os::active_processor_count() {
"which may exceed available processors", strerror(errno), cpu_count);
}
if (cpus_p != &cpus) {
if (cpus_p != &cpus) { // can only be true when CPU_ALLOC used
CPU_FREE(cpus_p);
}