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cgroup: Use system reported "unlimited" value for comparison

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With kernel 3.18 (since commit 3e32cb2e0a12b6915056ff04601cf1bb9b44f967)
the "unlimited" value for cgroup memory limits has changed once again as
its byte value is now computed from a page counter.
The new "unlimited" value reported by the cgroup fs is therefore 2**51-1
pages which is (VIR_DOMAIN_MEMORY_PARAM_UNLIMITED - 3072). This results
e.g. in virsh memtune displaying 9007199254740988 instead of unlimited
for the limits.

This patch uses the value of memory.limit_in_bytes from the cgroup
memory root which is the system's "real" unlimited value for comparison.

See also libvirt commit 231656bbeb9e4d3bedc44362784c35eee21cf0f4 for the
history for kernel 3.12 and before.

Signed-off-by: Viktor Mihajlovski <mihajlov@linux.vnet.ibm.com>
This commit is contained in:
Viktor Mihajlovski 2016-12-06 13:03:29 +01:00 committed by Martin Kletzander
parent 22f7ceb695
commit ac8ac9e052
1 changed files with 55 additions and 18 deletions
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73
src/util/vircgroup.c
View File

@ -60,6 +60,7 @@
#include "virsystemd.h"
#include "virtypedparam.h"
#include "virhostcpu.h"
#include "virthread.h"
VIR_LOG_INIT("util.cgroup");
@ -2452,6 +2453,51 @@ virCgroupGetBlkioDeviceWeight(virCgroupPtr group,
}
/*
* Retrieve the "memory.limit_in_bytes" value from the memory controller
* root dir. This value cannot be modified by userspace and therefore
* is the maximum limit value supported by cgroups on the local system.
* Returns this value scaled to KB or falls back to the original
* VIR_DOMAIN_MEMORY_PARAM_UNLIMITED. Either way, remember the return
* value to avoid unnecessary cgroup filesystem access.
*/
static unsigned long long int virCgroupMemoryUnlimitedKB;
static virOnceControl virCgroupMemoryOnce = VIR_ONCE_CONTROL_INITIALIZER;
static void
virCgroupMemoryOnceInit(void)
{
virCgroupPtr group;
unsigned long long int mem_unlimited = 0ULL;
if (virCgroupNew(-1, "/", NULL, -1, &group) < 0)
goto cleanup;
if (!virCgroupHasController(group, VIR_CGROUP_CONTROLLER_MEMORY))
goto cleanup;
ignore_value(virCgroupGetValueU64(group,
VIR_CGROUP_CONTROLLER_MEMORY,
"memory.limit_in_bytes",
&mem_unlimited));
cleanup:
virCgroupFree(&group);
virCgroupMemoryUnlimitedKB = mem_unlimited >> 10;
}
static unsigned long long int
virCgroupGetMemoryUnlimitedKB(void)
{
if (virOnce(&virCgroupMemoryOnce, virCgroupMemoryOnceInit) < 0)
VIR_DEBUG("Init failed, will fall back to defaults.");
if (virCgroupMemoryUnlimitedKB)
return virCgroupMemoryUnlimitedKB;
else
return VIR_DOMAIN_MEMORY_PARAM_UNLIMITED;
}
/**
* virCgroupSetMemory:
*
@ -2534,20 +2580,17 @@ int
virCgroupGetMemoryHardLimit(virCgroupPtr group, unsigned long long *kb)
{
long long unsigned int limit_in_bytes;
int ret = -1;
if (virCgroupGetValueU64(group,
VIR_CGROUP_CONTROLLER_MEMORY,
"memory.limit_in_bytes", &limit_in_bytes) < 0)
goto cleanup;
return -1;
*kb = limit_in_bytes >> 10;
if (*kb > VIR_DOMAIN_MEMORY_PARAM_UNLIMITED)
if (*kb >= virCgroupGetMemoryUnlimitedKB())
*kb = VIR_DOMAIN_MEMORY_PARAM_UNLIMITED;
ret = 0;
cleanup:
return ret;
return 0;
}
@ -2596,20 +2639,17 @@ int
virCgroupGetMemorySoftLimit(virCgroupPtr group, unsigned long long *kb)
{
long long unsigned int limit_in_bytes;
int ret = -1;
if (virCgroupGetValueU64(group,
VIR_CGROUP_CONTROLLER_MEMORY,
"memory.soft_limit_in_bytes", &limit_in_bytes) < 0)
goto cleanup;
return -1;
*kb = limit_in_bytes >> 10;
if (*kb > VIR_DOMAIN_MEMORY_PARAM_UNLIMITED)
if (*kb >= virCgroupGetMemoryUnlimitedKB())
*kb = VIR_DOMAIN_MEMORY_PARAM_UNLIMITED;
ret = 0;
cleanup:
return ret;
return 0;
}
@ -2658,20 +2698,17 @@ int
virCgroupGetMemSwapHardLimit(virCgroupPtr group, unsigned long long *kb)
{
long long unsigned int limit_in_bytes;
int ret = -1;
if (virCgroupGetValueU64(group,
VIR_CGROUP_CONTROLLER_MEMORY,
"memory.memsw.limit_in_bytes", &limit_in_bytes) < 0)
goto cleanup;
return -1;
*kb = limit_in_bytes >> 10;
if (*kb > VIR_DOMAIN_MEMORY_PARAM_UNLIMITED)
if (*kb >= virCgroupGetMemoryUnlimitedKB())
*kb = VIR_DOMAIN_MEMORY_PARAM_UNLIMITED;
ret = 0;
cleanup:
return ret;
return 0;
}