9:08 a.m.
On Wed, Aug 13, 2008 at 12:50:33PM +0400, Evgeniy Sokolov wrote:
> OpenVZ has several parameters for memory management. All of them can be
> configured independetly.
>
> Patch allow to get configuration of memory from container config and
> then calculate total usage of memory.
>
> It is open question how to manage memory?
Basically the 'memory' as shown by libvirt should correspond to
the 'Total' seen inside the guest when running 'free'.
eg
# free
total used free shared buffers cached
Mem: 524288 34676 489612 0 0 0
-/+ buffers/cache: 34676 489612
Swap: 0 0 0
In this case 'memory' is 524288 kb.
This looks to correspond to OpenVZs 'PRIVVMPAGES' pages parameter.
It may
be configured what will be shown in /proc/meminfo inside container.
Memory from node, total memory or privvmpages. Privvmpages is default.
> +openvzFreeUbParam(struct openvz_ub_param *ub)
> +{
> + if (ub == NULL)
> + return;
> +#define FREE_P(x) if (ub->x != NULL) VIR_FREE(ub->x);
This is not required. VIR_FREE is happy to accept a NULL
and will do nothing. Just call VIR_FREE directly without
testing for != NULL.
> +/* calculate guaranteed memory for container
> +*/
> +int
> +openvzUb2Memory(struct openvz_ub_param *ub, unsigned long *memory)
> +{
> + unsigned long lowmem, mem, allmem;
> +
> + if (ub->oomguarpages == NULL ||
> + ub->kmemsize == NULL ||
> + ub->tcpsndbuf == NULL ||
> + ub->tcprcvbuf == NULL ||
> + ub->othersockbuf == NULL ||
> + ub->dgramrcvbuf == NULL ||
> + ub->lockedpages == NULL)
> + return -1;
> +
> + lowmem = ub->kmemsize->limit +
> + ub->tcpsndbuf->limit +
> + ub->tcprcvbuf->limit +
> + ub->othersockbuf->limit +
> + ub->dgramrcvbuf->limit +
> + ub->lockedpages->limit * get_pagesize();
> +
> + mem = ub->oomguarpages->barrier * get_pagesize();
> + allmem = mem + lowmem; //in bytes
> + *memory = allmem / 1024; //in kb
Summing all the different memory limits together is wrong - this will
make it impossible to implement a 'setMemory' operation because you've
now no way of deciding which parameter to set.
It is correct calcuation of total
memory.
Because of non-obvious implenetation of 'setMemory', I have asked 'how
to manage memory' in begining.
I propouse to set some portion of 'memory' to each limit.
In my testing the total memory inside a OpenVZ container seems to
correspond to the 'lockedpages' parameter, so we should just return
that value.
How did you get total memory?
Most big part of memory is oomguarpages (by default). Lockedpages is
about %1.
Since you convert to 'bytes' before converting back into kb, you'll
potentially overflow a 'long' on 32-bit platforms. You should use
'unsigned long long' instead to be safe.
yes, you right.
> +int
> +openvzUb2MaxMemory(struct openvz_ub_param *ub, unsigned long *memory)
> +{
> + unsigned long lowmem, mem, allmem;
> +
> + if (ub->privvmpages == NULL ||
> + ub->kmemsize == NULL ||
> + ub->tcpsndbuf == NULL ||
> + ub->tcprcvbuf == NULL ||
> + ub->othersockbuf == NULL ||
> + ub->dgramrcvbuf == NULL ||
> + ub->lockedpages == NULL)
> + return -1;
> +
> + lowmem = ub->kmemsize->limit +
> + ub->tcpsndbuf->limit +
> + ub->tcprcvbuf->limit +
> + ub->othersockbuf->limit +
> + ub->dgramrcvbuf->limit +
> + ub->lockedpages->limit * get_pagesize();
> +
> + mem = ub->privvmpages->barrier * get_pagesize();
> + allmem = mem + lowmem; //in bytes
> + *memory = allmem / 1024; //in kb
Likewise this should simply use the lockedpages parameter I believe.
What is the difference between a 'barrier' and a 'limit' in openvz
config ? Would it make sense to map 'memory' to the 'barrier' and
'maxmemory' to the 'limit' ?
Barrier & limit are soft and hard
limits.
Barrier is guarantee availability of resources. When resource is grown
up to barrier, it can grow more resurce within grace period, but not
more than limit.
Memory for application:
oomguarpages & vmguarpages - barrier has matter. It is guarantee number
of pages. Limits should be always very big - 2147483647.
When the whole node is in out of memory, kernel may don't allow to
allocate memory or kill container process.
Container may allocate more memory if memory on whole node is available,
but no more than privvmpages.
>
> @@ -262,6 +264,10 @@ static int openvzDomainGetInfo(virDomain
> }
> }
>
> + openvzGetMemory(dom->conn, strtoI(dom->name), &(info->memory)) ;
> + openvzGetMaxMemory(dom->conn, strtoI(dom->name), &(info->maxMem))
;
Can't you use 'vm->vpsid' and avoid the strtoI() call ?
vm->vpsid = -1 when VM is stoped.
It seems it would be more efficient to call openvzReadUbParams()
and openvzUb2Memory() & openvzUb2MaxMemory directly, rather than
calling out to openvzGetMemory() and openvzGetMaxMemory() since
it would avoid reading the config file twice - you can also get
the nrVirtCPUs at the same time.
Yes, we can read memory once. But get number of
CPUs is little complicated.
Regards,
Daniel