[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Bug - Xen 4.3 - xl ignores maxmem setting in domU config file
On Tue, Oct 29, 2013 at 11:06:01AM +0000, Andrew Cooper wrote: > On 29/10/13 10:59, Wei Liu wrote: > > On Tue, Oct 29, 2013 at 10:26:00AM +0000, James Dingwall wrote: > >> Hi, > >> > >> I am having some memory ballooning problems which only seem to have > >> appeared since upgrading to Xen 4.3. In short if I set the domU > >> configuration file as: > >> > >> memory = 512 > >> maxmem = 1024 > >> > >> Then even under memory pressure the guest domain does not balloon past > >> the value of the 'memory' parameter. > >> > >> xl info shows plenty of available memory in dom0: > >> total_memory : 32767 > >> free_memory : 12445 > >> > >> > >> xl list -l on the domain shows: > >> "max_memkb": 1048576, > >> "target_memkb": 524288, > >> > > This is parsed from your config file so they should always look OK to > > you. > > > > Does the following patch help? > > > > Git blame tells me the change to set maxmem to target_memkb was > > introduced 4 years ago so I suspect there's reason to do that. If we > > cannot fix it here we need to insert the corresponding call later. > > When setmaxmem sets a limit lower than current, the domain can strictly > only balloon down until it is equal to or under the new limit. > > Performing a setmaxmem hypercall to info->target_memkb will prevent from > domain from ballooning down then back up a bit, when it has been asked > to balloon down a lot; i.e. it must strictly balloon down to the limit > it has been given. > > Therefore, I am not sure this change is valid. > > ~Andrew > Looking at the changeset 9905ac that introduced target_memkb, target_memkb was always set to max_memkb, so my guess is that the purpose was still to use max_memkb to be max memory limit. Probably later changes to that portion of code altered that behavior. The use of target_memkb in xc_domain_setmaxmem looks logically wrong to me anyway... Stefano, thoughts? Wei. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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