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8170888: [linux] Experimental support for cgroup memory limits in container (ie Docker) environments

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Set apparent physical memory to cgroup memory limit when UseCGroupMemoryLimitForHeap is true

Reviewed-by: acorn, kbarrett
This commit is contained in:
Christine Flood 2016-12-12 15:41:50 -05:00 committed by David Holmes
parent c9a8dbfa25
commit 6fd85f1084
2 changed files with 31 additions and 1 deletions
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28
hotspot/src/share/vm/runtime/arguments.cpp
View File

@ -2038,10 +2038,36 @@ julong Arguments::limit_by_allocatable_memory(julong limit) {
static const size_t DefaultHeapBaseMinAddress = HeapBaseMinAddress;
void Arguments::set_heap_size() {
const julong phys_mem =
julong phys_mem =
FLAG_IS_DEFAULT(MaxRAM) ? MIN2(os::physical_memory(), (julong)MaxRAM)
: (julong)MaxRAM;
// Experimental support for CGroup memory limits
if (UseCGroupMemoryLimitForHeap) {
// This is a rough indicator that a CGroup limit may be in force
// for this process
const char* lim_file = "/sys/fs/cgroup/memory/memory.limit_in_bytes";
FILE *fp = fopen(lim_file, "r");
if (fp != NULL) {
julong cgroup_max = 0;
int ret = fscanf(fp, JULONG_FORMAT, &cgroup_max);
if (ret == 1 && cgroup_max > 0) {
// If unlimited, cgroup_max will be a very large, but unspecified
// value, so use initial phys_mem as a limit
log_info(gc, heap)("Setting phys_mem to the min of cgroup limit ("
JULONG_FORMAT "MB) and initial phys_mem ("
JULONG_FORMAT "MB)", cgroup_max/M, phys_mem/M);
phys_mem = MIN2(cgroup_max, phys_mem);
} else {
warning("Unable to read/parse cgroup memory limit from %s: %s",
lim_file, errno != 0 ? strerror(errno) : "unknown error");
}
fclose(fp);
} else {
warning("Unable to open cgroup memory limit file %s (%s)", lim_file, strerror(errno));
}
}
// If the maximum heap size has not been set with -Xmx,
// then set it as fraction of the size of physical memory,
// respecting the maximum and minimum sizes of the heap.

4
hotspot/src/share/vm/runtime/globals.hpp
View File

@ -2037,6 +2037,10 @@ public:
"MaxRAM / MaxRAMFraction") \
range(0, max_uintx) \
\
experimental(bool, UseCGroupMemoryLimitForHeap, false, \
"Use CGroup memory limit as physical memory limit for heap " \
"sizing") \
\
product(uintx, MaxRAMFraction, 4, \
"Maximum fraction (1/n) of real memory used for maximum heap " \
"size") \