Re: [libvirt] [PATCH v3 04/13] XML parsing for memory tunables

On Mon, 4 Oct 2010 12:16:42 +0530, Balbir Singh <balbir(a)linux.vnet.ibm.com&gt; wrote: > * Nikunj A. Dadhania <nikunj(a)linux.vnet.ibm.com&gt; [2010-09-28 15:26:30]: <snip> > > + /* Extract other memory tunables */ > > + if (virXPathULong("string(./memtune/hard_limit)", ctxt, > > + &def->mem.hard_limit) < 0) > > + def->mem.hard_limit = 0; > > + > > + if (virXPathULong("string(./memtune/soft_limit[1])", ctxt, > > + &def->mem.soft_limit) < 0) > > + def->mem.soft_limit = 0; > > + > > + if (virXPathULong("string(./memtune/min_guarantee[1])", ctxt, > > + &def->mem.min_guarantee) < 0) > > + def->mem.min_guarantee = 0; > > + > > + if (virXPathULong("string(./memtune/swap_hard_limit[1])", ctxt, > > + &def->mem.swap_hard_limit) < 0) > > + def->mem.swap_hard_limit = 0; > > + > > Quick question, does 0 represent invalid values? If configuration file does not provide any value, we set this to 0, we do not call the lower layer calls in this case. > I'd presume you'd > want to use something like -1. We support unsigned long long for the > values to be set (64 bit signed), unlimited translates to 2^63 - 1, is > ULong sufficient to represent that value? The unit here is KB, so we can have till 2^42 bytes. So to answer you question, no it does not represent 64 bit signed. I guess this should not be an issue to support if needed. I understand that in case of cgroup unlimited is (-1), but again that would be cgroup specific at this level. I need to think of some way to address this independent of the lower layer. > > + unsigned long hard_limit; > > + unsigned long soft_limit; > > + unsigned long min_guarantee; > > + unsigned long swap_hard_limit; > > The hard_limit, soft_limit, swap_hard_limit are s64 and the value is > in bytes. What is the unit supported in this implementation?