3:29 p.m.
The code that calls virCgroupSetCpuShares() and virCgroupGetCpuShares()
is repeated in 4 different places. Let's put it in a new
virCgroupSetupCpuShares() to avoid code repetition.
There's a reason of why we execute a Get in the same value we
just executed Set, explained in detail by commit 97814d8ab3.
Let's add a gist of the reasoning behind it as a comment in
this new function as well.
Signed-off-by: Daniel Henrique Barboza <danielhb413(a)gmail.com>
---
src/libvirt_private.syms | 1 +
src/lxc/lxc_cgroup.c | 5 +----
src/lxc/lxc_driver.c | 6 ++----
src/qemu/qemu_cgroup.c | 5 ++---
src/qemu/qemu_driver.c | 5 +----
src/util/vircgroup.c | 20 ++++++++++++++++++++
src/util/vircgroup.h | 2 ++
7 files changed, 29 insertions(+), 15 deletions(-)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index a58a5ed78b..8be5fe7d9f 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1731,6 +1731,7 @@ virCgroupSetupBlkioDeviceWeight;
virCgroupSetupBlkioDeviceWriteBps;
virCgroupSetupBlkioDeviceWriteIops;
virCgroupSetupCpusetCpus;
+virCgroupSetupCpuShares;
virCgroupSupportsCpuBW;
virCgroupTerminateMachine;
diff --git a/src/lxc/lxc_cgroup.c b/src/lxc/lxc_cgroup.c
index 618063bf43..4c8464bd97 100644
--- a/src/lxc/lxc_cgroup.c
+++ b/src/lxc/lxc_cgroup.c
@@ -40,10 +40,7 @@ static int virLXCCgroupSetupCpuTune(virDomainDefPtr def,
{
if (def->cputune.sharesSpecified) {
unsigned long long val;
- if (virCgroupSetCpuShares(cgroup, def->cputune.shares) < 0)
- return -1;
-
- if (virCgroupGetCpuShares(cgroup, &val) < 0)
+ if (virCgroupSetupCpuShares(cgroup, def->cputune.shares, &val) < 0)
return -1;
def->cputune.shares = val;
}
diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c
index 439cc317c6..e66aa7b8f5 100644
--- a/src/lxc/lxc_driver.c
+++ b/src/lxc/lxc_driver.c
@@ -1959,10 +1959,8 @@ lxcDomainSetSchedulerParametersFlags(virDomainPtr dom,
if (STREQ(param->field, VIR_DOMAIN_SCHEDULER_CPU_SHARES)) {
if (def) {
unsigned long long val;
- if (virCgroupSetCpuShares(priv->cgroup, params[i].value.ul) < 0)
- goto endjob;
-
- if (virCgroupGetCpuShares(priv->cgroup, &val) < 0)
+ if (virCgroupSetupCpuShares(priv->cgroup, params[i].value.ul,
+ &val) < 0)
goto endjob;
def->cputune.shares = val;
diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c
index ee08b99064..f969469931 100644
--- a/src/qemu/qemu_cgroup.c
+++ b/src/qemu/qemu_cgroup.c
@@ -894,11 +894,10 @@ qemuSetupCpuCgroup(virDomainObjPtr vm)
if (vm->def->cputune.sharesSpecified) {
unsigned long long val;
- if (virCgroupSetCpuShares(priv->cgroup, vm->def->cputune.shares) <
0)
+ if (virCgroupSetupCpuShares(priv->cgroup, vm->def->cputune.shares,
+ &val) < 0)
return -1;
- if (virCgroupGetCpuShares(priv->cgroup, &val) < 0)
- return -1;
if (vm->def->cputune.shares != val) {
vm->def->cputune.shares = val;
if (virTypedParamsAddULLong(&eventParams, &eventNparams,
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index c1a79dcda6..e9feb50220 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -10648,10 +10648,7 @@ qemuDomainSetSchedulerParametersFlags(virDomainPtr dom,
if (STREQ(param->field, VIR_DOMAIN_SCHEDULER_CPU_SHARES)) {
if (def) {
unsigned long long val;
- if (virCgroupSetCpuShares(priv->cgroup, value_ul) < 0)
- goto endjob;
-
- if (virCgroupGetCpuShares(priv->cgroup, &val) < 0)
+ if (virCgroupSetupCpuShares(priv->cgroup, value_ul, &val) < 0)
goto endjob;
def->cputune.shares = val;
diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c
index dcbd55c0f1..a1093e410d 100644
--- a/src/util/vircgroup.c
+++ b/src/util/vircgroup.c
@@ -3681,3 +3681,23 @@ virCgroupSetupCpusetCpus(virCgroupPtr cgroup, virBitmapPtr
cpumask)
return 0;
}
+
+
+/* Per commit 97814d8ab3, the Linux kernel can consider a 'shares'
+ * value of '0' and '1' as 2, and any value larger than a maximum
+ * is reduced to maximum.
+ *
+ * The 'realValue' pointer holds the actual 'shares' value set by
+ * the kernel if the function returned success. */
+int
+virCgroupSetupCpuShares(virCgroupPtr cgroup, unsigned long long shares,
+ unsigned long long *realValue)
+{
+ if (virCgroupSetCpuShares(cgroup, shares) < 0)
+ return -1;
+
+ if (virCgroupGetCpuShares(cgroup, realValue) < 0)
+ return -1;
+
+ return 0;
+}
diff --git a/src/util/vircgroup.h b/src/util/vircgroup.h
index 55132dedb6..305d5c9853 100644
--- a/src/util/vircgroup.h
+++ b/src/util/vircgroup.h
@@ -222,6 +222,8 @@ virCgroupGetDomainTotalCpuStats(virCgroupPtr group,
int virCgroupSetCpuShares(virCgroupPtr group, unsigned long long shares);
int virCgroupGetCpuShares(virCgroupPtr group, unsigned long long *shares);
+int virCgroupSetupCpuShares(virCgroupPtr cgroup, unsigned long long shares,
+ unsigned long long *realValue);
int virCgroupSetCpuCfsPeriod(virCgroupPtr group, unsigned long long cfs_period);
int virCgroupGetCpuCfsPeriod(virCgroupPtr group, unsigned long long *cfs_period);
--
2.24.1