Re: [Xen-devel] xl mem-max error

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Fri, Nov 07, 2014 at 09:21:38AM -0500, Zhigang Wang wrote:
> On 11/07/2014 06:05 AM, Wei Liu wrote:
> > On Thu, Nov 06, 2014 at 05:17:42PM -0500, Zhigang Wang wrote:
> >> Hi,
> >>
> >> I get this error:
> >>
> >>     # xl mem-max 3 700
> >>     libxl: error: libxl.c:4549:libxl_domain_setmaxmem: memory_static_max 
> >> must be greater than or or equal to memory_dynamic_max
> >>     : Success
> >>     cannot set domid 3 static max memory to : 700
> >>
> > 
> > What's your expected behaviour? What's your end goal?
> 
> I expect: after start a VM with memory = 700, then I can do:
> 
>    # xl mem-max <domain> 700
> 
> In our code, we always check (libxl.c):
> 
> 
>     if (max_memkb < memorykb) {
>         LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "memory_static_max must be 
> greater than or or equal to memory_dynamic_max\n");
>         goto out;
>     }
> 
> As target memory is always bigger than static-max in xenstore (from my test, 
> for both pv and hvm):
> 
>     /local/domain/3/memory/static-max = "716800"
>     /local/domain/3/memory/target = "716801
> 
> So it will not success.
> 
> Also I think target memory bigger than static-max seems not right.
> 

This does look bogus, which may cause the guest to try to balloon up
over limit. At the very least, we should fix make target as big as
statix-max?

Ian and Ian, any thought how this bug came into being? I think we should
fix this for 4.5, but I don't think I know enough of how memory target
is expected to behave.

Wei.

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