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Re: [libvirt] [PATCH] openvz: read vmguarpages/privvmpages to set memory tunables [v2]



On 04/26/2012 05:16 AM, Guido Günther wrote:
> ---
> This is a reworked version of the patch already sent, now adding
> handling for "unlimited" (represented by LONG_MAX in openvz) as well as
> a schema testcase. I also switched all value to unsigned long long to
> avoid overflows.
> Note that privvmpages is the amount of memory available to the
> application. The total memory usage of the container might be higher due
> to used kernel memory. This does probably warrant an extra tunable
> later. O.k. to apply?
> Cheers,
>  -- Guido
> 

>  
> +static int
> +openvzReadMemConf(virDomainDefPtr def, int veid)
> +{
> +    int ret;
> +    char *temp = NULL;
> +    unsigned long long barrier, limit;
> +    const char *param;
> +    unsigned long kb_per_pages;
> +
> +    kb_per_pages = sysconf(_SC_PAGESIZE) / 1024;

In general, you should be prepared for sysconf() to fail...

> +    if (kb_per_pages == -1) {

but you already divided by 1024, so failure will no longer show as -1 at
this point.

> +
> +    if (sscanf(output, "%llu %llu", barrier, limit) != 2) {

sscanf() can't detect overflow.  I'd rather use virStrToLong_ull() for
safety.


> +
> +static int
> +openvzDomainGetMemoryParameters(virDomainPtr domain,
> +                                virTypedParameterPtr params,
> +                                int *nparams,
> +                                unsigned int flags)
> +{
> +    int i, result = -1;
> +    const char *name;
> +    long kb_per_pages;
> +    unsigned long long barrier, limit, val;
> +
> +    virCheckFlags(0, -1);
> +
> +    kb_per_pages = sysconf(_SC_PAGESIZE) / 1024;
> +    if (kb_per_pages == -1) {

Oops, another inability to detect failure.

> +
> +static int
> +openvzDomainSetMemoryParameters(virDomainPtr domain,
> +                                virTypedParameterPtr params,
> +                                int nparams,
> +                                unsigned int flags)
> +{
> +    int i, result = -1;
> +    long kb_per_pages;
> +
> +    kb_per_pages = sysconf(_SC_PAGESIZE) / 1024;
> +    if (kb_per_pages == -1) {

And again.

But the bulk of this patch looks reasonable.  Would you mind respinning
a v2 to address the nits, and we can probably get this in 0.9.12 even if
it misses rc1.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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