On 07/12/2012 11:37 AM, Osier Yang wrote:
> On 2012年07月12日 17:19, Hu Tao wrote:
>> On Thu, Jul 12, 2012 at 05:03:52PM +0800, Osier Yang wrote:
>>> Setting hard_limit larger than previous swap_hard_limit must fail,
>>> it's not that good if one wants to change the swap_hard_limit
>>> and hard_limit together. E.g.
>>>
>>> % virsh memtune rhel6
>>> hard_limit : 1000000
>>> soft_limit : 1000000
>>> swap_hard_limit: 1000000
>>>
>>> % virsh memtune rhel6 --hard-limit 1000020 --soft-limit 1000020 \
>>> --swap-hard-limit 1000020 --live
>>>
>>> This patch reoder the limits setting to set the swap_hard_limit
>>> first.
>>> ---
>>> src/qemu/qemu_driver.c | 26 +++++++++++++-------------
>>> 1 files changed, 13 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
>>> index dc04d13..1abdd27 100644
>>> --- a/src/qemu/qemu_driver.c
>>> +++ b/src/qemu/qemu_driver.c
>>> @@ -6625,43 +6625,43 @@ qemuDomainSetMemoryParameters(virDomainPtr dom,
>>> for (i = 0; i< nparams; i++) {
>>> virTypedParameterPtr param =¶ms[i];
>>
>> Does this patch make any difference if the order of elements of params[]
>> doesn't change?
>
> Oops, right. I rushed, except qemu, lxc openvz also support memtune,
> means I need a v2 anyway. Thanks.
>
One more thing. If the limit goes down it has to be set in the order:
1. soft_limit
2. hard_limit
3. swap_hard_limit
because otherwise you'll get to the same problems. I had something like
this in mind:
for each parameter -- check if it can be set (according to the current
values):
- yes) set it
- no) check if the parameter blocking the current one is being changed
as well:
- no) fail
- yes) prefer the parameter blocking the current one
Few more approaches (just to get it out of my head):
- set the values twice with ignoring errors in the first pass (ugly)
- check and sort all the parameters and then change them (overhead?)
- set the values to max/unlimited and then set them in a predefined
order (soft, hard, memsw).
Have a nice day,
Martin
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