[libvirt] [PATCH] memtune: Add min_guarantee to the virsh tool

[Matthias Bolte]

2010/10/20 Nikunj A. Dadhania <nikunj at linux.vnet.ibm.com>:
> On Tue, 19 Oct 2010 15:49:05 +0200, Daniel Veillard <veillard at redhat.com> wrote:
>> On Tue, Oct 19, 2010 at 03:00:21PM +0200, Matthias Bolte wrote:
>> > 2010/10/18 Nikunj A. Dadhania <nikunj at linux.vnet.ibm.com>:
> [...]
>> > > tools/virsh.c: Add new memory tunable "min_guarantee", currently the user
>> > > would be ESX.
>> >
>> > Well, who said ESX could support this? :)
>> >
>> > I didn't, I just said that you added min_guarantee to libvirt, but
>> > didn't expose it in virsh.
>>
>>   Hum ... I assumed there was an use case for it.
>> On the other hand since it's now part of libvirt API as
>> VIR_DOMAIN_MEMORY_MIN_GUARANTEE enum value, it's cleaner to have it
>> available at the virsh level. If there is really no use (or no potential
>> use in a reasonable future) for it, the best is to remove it altogether
>> from the API and the of virsh, before next week release.
>>
>>   Nikunj I could not find any reference to "the well-known tunable"
>> min_guarantee (it's clearly not well known ...) but can you tell us
>> where this comes from ?
>>
> VMWare:
> =======
> Reservation: Gauranteed lower bound on the amount of the physical memory that
>             the host reserves for the VM even in case of the overcommit. The
>             VM is allowed to allocate till this level and after it has hit
>             the reservation, those pages are not reclaimed. In case, if guest
>             is not using till the reservation, the host can use that portion
>             of memory.
>
> And maybe in future cgroups.

Sorry, seems like I really did say that, but didn't remember doing so :(

Yes, reservation maps to min_guarantee :)

I'll add this to the ESX driver soon, so that we have at least one
user for each memtuneable.

Matthias