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8241423: NUMA APIs fail to work in dockers due to dependent syscalls are disabled by default #4205

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8241423: NUMA APIs fail to work in dockers due to dependent syscalls are disabled by default #4205

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8241423: NUMA APIs fail to work in dockers due to dependent syscalls …
DamonFool May 26, 2021
ea84a32
Remove os::Linux namespace for numa_syscall_check()
DamonFool May 26, 2021
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18 changes: 17 additions & 1 deletion src/hotspot/os/linux/os_linux.cpp
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Expand Up @@ -2962,7 +2962,8 @@ void* os::Linux::libnuma_v2_dlsym(void* handle, const char* name) {
}

bool os::Linux::libnuma_init() {
if (sched_getcpu() != -1) { // Requires sched_getcpu() support
// Requires sched_getcpu() and numa dependent syscalls support
if ((sched_getcpu() != -1) && numa_syscall_check()) {
void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
if (handle != NULL) {
set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
Expand Down Expand Up @@ -4477,6 +4478,21 @@ void os::Linux::numa_init() {
}
}

// Check numa dependent syscalls
bool os::Linux::numa_syscall_check() {
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This can just be a static function in the file rather then being in the os::Linux "namespace"

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This can just be a static function in the file rather then being in the os::Linux "namespace"

Updated.
Thanks.

// NUMA APIs depend on several syscalls. E.g., get_mempolicy is required for numa_get_membind and
// numa_get_interleave_mask. But these dependent syscalls can be unsupported for various reasons.
// Especially in dockers, get_mempolicy is not allowed with the default configuration. So it's necessary
// to check whether the syscalls are available. Currently, only get_mempolicy is checked since checking
// others like mbind would cause unexpected side effects.
int dummy = 0;
if (syscall(SYS_get_mempolicy, &dummy, NULL, 0, (void*)&dummy, 3) == -1) {
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Is this SYS_get_mempolicy symbol guaranteed to be available on our supported Linux versions? See earlier in the file for how we handle SYS_gettid and SYS_getcpu.

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Is this SYS_get_mempolicy symbol guaranteed to be available on our supported Linux versions? See earlier in the file for how we handle SYS_gettid and SYS_getcpu.

I think it's OK to use the symbol directly since we have used it in ZGC [1].
Thanks.

[1] https://github.com/openjdk/jdk/blob/master/src/hotspot/os/linux/gc/z/zSyscall_linux.cpp#L39

return false;
}

return true;
}

// this is called _after_ the global arguments have been parsed
jint os::init_2(void) {

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1 change: 1 addition & 0 deletions src/hotspot/os/linux/os_linux.hpp
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Expand Up @@ -180,6 +180,7 @@ class Linux {

private:
static void numa_init();
static bool numa_syscall_check();
static void expand_stack_to(address bottom);

typedef int (*sched_getcpu_func_t)(void);
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