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.
> +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.
In my testing the total memory inside a OpenVZ container seems to
correspond to the 'lockedpages' parameter, so we should just return
that value.
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.
> +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' ?
>
> @@ -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 ?
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.
Regards,
Daniel
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