[libvirt] [PATCH v2 1/2] LXC: add support for persistent config in lxcDomainSetMemoryFlags
John Ferlan
jferlan at redhat.com
Tue Aug 12 18:09:43 UTC 2014
On 07/30/2014 11:41 PM, Chen Hanxiao wrote:
> Currently, setmaxmem return success on an active
> domain, but nothing happened.
Not quite true... Prior to these changes...
# virsh -c lxc:/// start vm1
# virsh -c lxc:/// dominfo vm1 | grep memory
Max memory: 500000 KiB
Used memory: 776 KiB
# virsh -c lxc:/// dumpxml vm1 | grep mem
<memory unit='KiB'>500000</memory>
# cat /sys/fs/cgroup/memory/machine.slice/*/memory.limit_in_bytes
512000000
# virsh -c lxc:/// setmaxmem vm1 525000
# virsh -c lxc:/// dominfo vm1 | grep memory
Max memory: 525000 KiB
Used memory: 776 KiB
# virsh -c lxc:/// dumpxml vm1 | grep mem
<memory unit='KiB'>525000</memory>
# cat /sys/fs/cgroup/memory/machine.slice/*/memory.limit_in_bytes
512000000
# virsh -c lxc:/// console vm1
Connected to domain vm1
Escape character is ^]
sh-4.2# grep Mem /proc/meminfo
MemTotal: 500000 kB
MemFree: 499076 kB
MemAvailable: 3629632 kB
#
Now I'll agree that technically what one expected to happen didn't since
it's not supported, but something did happen :-)... And of course after
a destroy the maxmem went back to 500000.
> This patch will disable this behaviour,
> also add support persistent config.
> And it will be used in a later patch.
FWIW:
I agree with Peter's observation from your v1 - the two patches should
be one as it is clearer that way what you are doing and leaves no doubt
why the flag is used
I do see that other drivers like qemu & libxl use the MEM_MAXIMUM flag.
So perhaps said differently -
"This patch changes the LXC driver setmaxmem function to support the
'--live', '--config', and '--current' flags by revectoring the code
through the setmem function using the VIR_DOMAIN_MEM_MAXIMUM flag. The
setmem code is refactored to handle both cases depending on the flag.
The changed maxmem code for the MEM_MAXIMUM path will not allow
modification to the memory values of an active guest unless the --config
switch is used."
>
> Signed-off-by: Chen Hanxiao <chenhanxiao at cn.fujitsu.com>
> ---
> v2: disable changing max memory on an active domain
> drop useless as_assert
>
> src/lxc/lxc_driver.c | 64 +++++++++++++++++++++++++++++++++-------------------
> 1 file changed, 41 insertions(+), 23 deletions(-)
>
> diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c
> index 9e12ecc..d99ab3b 100644
> --- a/src/lxc/lxc_driver.c
> +++ b/src/lxc/lxc_driver.c
> @@ -721,10 +721,10 @@ static int lxcDomainSetMemoryFlags(virDomainPtr dom, unsigned long newmem,
> virLXCDomainObjPrivatePtr priv;
> virLXCDriverPtr driver = dom->conn->privateData;
> virLXCDriverConfigPtr cfg = NULL;
> - unsigned long oldmax = 0;
>
> virCheckFlags(VIR_DOMAIN_AFFECT_LIVE |
> - VIR_DOMAIN_AFFECT_CONFIG, -1);
> + VIR_DOMAIN_AFFECT_CONFIG |
> + VIR_DOMAIN_MEM_MAXIMUM, -1);
>
> if (!(vm = lxcDomObjFromDomain(dom)))
> goto cleanup;
> @@ -743,32 +743,50 @@ static int lxcDomainSetMemoryFlags(virDomainPtr dom, unsigned long newmem,
> &persistentDef) < 0)
> goto cleanup;
>
I see the next set of changes is essentially cut-n-pasted from qemu,
although the changes after the else are the same as the former setmem
function - it's just the git diff that obfuscates that.
The changes do work as I'd expect, so ACK from that point of view.
I can merge the two patches for you and commit, but I'll give it a bit
to make sure no one else has concerns
John
> - if (flags & VIR_DOMAIN_AFFECT_LIVE)
> - oldmax = vm->def->mem.max_balloon;
> - if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
> - if (!oldmax || oldmax > persistentDef->mem.max_balloon)
> - oldmax = persistentDef->mem.max_balloon;
> - }
> + if (flags & VIR_DOMAIN_MEM_MAXIMUM) {
> + if (flags & VIR_DOMAIN_AFFECT_LIVE) {
> + virReportError(VIR_ERR_OPERATION_INVALID, "%s",
> + _("Cannot resize the max memory "
> + "on an active domain"));
> + goto cleanup;
> + }
>
> - if (newmem > oldmax) {
> - virReportError(VIR_ERR_INVALID_ARG,
> - "%s", _("Cannot set memory higher than max memory"));
> - goto cleanup;
> - }
> + if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
> + persistentDef->mem.max_balloon = newmem;
> + if (persistentDef->mem.cur_balloon > newmem)
> + persistentDef->mem.cur_balloon = newmem;
> + if (virDomainSaveConfig(cfg->configDir, persistentDef) < 0)
> + goto cleanup;
> + }
> + } else {
> + unsigned long oldmax = 0;
>
> - if (flags & VIR_DOMAIN_AFFECT_LIVE) {
> - if (virCgroupSetMemory(priv->cgroup, newmem) < 0) {
> - virReportError(VIR_ERR_OPERATION_FAILED,
> - "%s", _("Failed to set memory for domain"));
> - goto cleanup;
> + if (flags & VIR_DOMAIN_AFFECT_LIVE)
> + oldmax = vm->def->mem.max_balloon;
> + if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
> + if (!oldmax || oldmax > persistentDef->mem.max_balloon)
> + oldmax = persistentDef->mem.max_balloon;
> }
> - }
>
> - if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
> - sa_assert(persistentDef);
> - persistentDef->mem.cur_balloon = newmem;
> - if (virDomainSaveConfig(cfg->configDir, persistentDef) < 0)
> + if (newmem > oldmax) {
> + virReportError(VIR_ERR_INVALID_ARG,
> + "%s", _("Cannot set memory higher than max memory"));
> goto cleanup;
> + }
> +
> + if (flags & VIR_DOMAIN_AFFECT_LIVE) {
> + if (virCgroupSetMemory(priv->cgroup, newmem) < 0) {
> + virReportError(VIR_ERR_OPERATION_FAILED,
> + "%s", _("Failed to set memory for domain"));
> + goto cleanup;
> + }
> + }
> +
> + if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
> + persistentDef->mem.cur_balloon = newmem;
> + if (virDomainSaveConfig(cfg->configDir, persistentDef) < 0)
> + goto cleanup;
> + }
> }
>
> ret = 0;
>
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