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6515172: Runtime.availableProcessors() ignores Linux taskset command

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Extract processor count from sched_getaffinity mask

Reviewed-by: dcubed, stuefe, gthornbr
This commit is contained in:
David Holmes 2016-01-29 05:32:12 -05:00
parent b41df1a2e7
commit 1875f65a54
4 changed files with 184 additions and 9 deletions
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81
hotspot/src/os/linux/vm/os_linux.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -32,6 +32,7 @@
#include "compiler/disassembler.hpp"
#include "interpreter/interpreter.hpp"
#include "jvm_linux.h"
#include "logging/log.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/filemap.hpp"
#include "mutex_linux.inline.hpp"
@ -106,6 +107,14 @@
# include <inttypes.h>
# include <sys/ioctl.h>
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#include <sched.h>
#undef _GNU_SOURCE
#else
#include <sched.h>
#endif
// if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling
// getrusage() is prepared to handle the associated failure.
#ifndef RUSAGE_THREAD
@ -4762,12 +4771,72 @@ void os::make_polling_page_readable(void) {
}
}
// 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.
// If it appears there may be more than 1024 processors then we do a
// dynamic check - see 6515172 for details.
// If anything goes wrong we fallback to returning the number of online
// processors - which can be greater than the number available to the process.
int os::active_processor_count() {
// Linux doesn't yet have a (official) notion of processor sets,
// so just return the number of online processors.
int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
return online_cpus;
cpu_set_t cpus; // can represent at most 1024 (CPU_SETSIZE) processors
cpu_set_t* cpus_p = &cpus;
int cpus_size = sizeof(cpu_set_t);
int configured_cpus = processor_count(); // upper bound on available cpus
int cpu_count = 0;
// To enable easy testing of the dynamic path on different platforms we
// introduce a diagnostic flag: UseCpuAllocPath
if (configured_cpus >= CPU_SETSIZE || UseCpuAllocPath) {
// kernel may use a mask bigger than cpu_set_t
log_trace(os)("active_processor_count: using dynamic path %s"
"- configured processors: %d",
UseCpuAllocPath ? "(forced) " : "",
configured_cpus);
cpus_p = CPU_ALLOC(configured_cpus);
if (cpus_p != NULL) {
cpus_size = CPU_ALLOC_SIZE(configured_cpus);
// zero it just to be safe
CPU_ZERO_S(cpus_size, cpus_p);
}
else {
// failed to allocate so fallback to online cpus
int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
log_trace(os)("active_processor_count: "
"CPU_ALLOC failed (%s) - using "
"online processor count: %d",
strerror(errno), online_cpus);
return online_cpus;
}
}
else {
log_trace(os)("active_processor_count: using static path - configured processors: %d",
configured_cpus);
}
// 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) {
cpu_count = CPU_COUNT_S(cpus_size, cpus_p);
}
else {
cpu_count = CPU_COUNT(cpus_p);
}
log_trace(os)("active_processor_count: sched_getaffinity processor count: %d", cpu_count);
}
else {
cpu_count = ::sysconf(_SC_NPROCESSORS_ONLN);
warning("sched_getaffinity failed (%s)- using online processor count (%d) "
"which may exceed available processors", strerror(errno), cpu_count);
}
if (cpus_p != &cpus) {
CPU_FREE(cpus_p);
}
assert(cpu_count > 0 && cpu_count <= processor_count(), "sanity check");
return cpu_count;
}
void os::set_native_thread_name(const char *name) {