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Re: [Xen-API] [Squeezd] Disabling some balancing features


  • To: 'Kakadu' <kakadu.hafanana@xxxxxxxxx>
  • From: Dave Scott <Dave.Scott@xxxxxxxxxxxxx>
  • Date: Tue, 23 Oct 2012 14:15:12 +0100
  • Accept-language: en-US
  • Acceptlanguage: en-US
  • Cc: "xen-api@xxxxxxxxxxxxx" <xen-api@xxxxxxxxxxxxx>
  • Delivery-date: Tue, 23 Oct 2012 13:15:28 +0000
  • List-id: User and development list for XCP and XAPI <xen-api.lists.xen.org>
  • Thread-index: Ac2uw5/TwW/eri43RemtpuIKHjbZcACXF0eg
  • Thread-topic: [Xen-API] [Squeezd] Disabling some balancing features

Hi,

Dave asked:
> > When you try to migrate to a host which hasn't got much free memory,
> do you intend to run the existing squeezing logic?

Kakadu replied:
> Nope, it should do nothing. In future another balooning daemon will be
> running and case there is not enough ememory never gonna happen. But
> now I'm trying to put right variables to vm params (to emulate
> presence of this future daemon).

In case it's useful: the most recent versions of xapi (found in XenServer 6.1 
and should be in XCP 1.6) can run without squeezed. So you can

service squeezed stop

and then when you try to start a VM, there won't be any squeezing at all. Your 
new daemon could do whatever it likes to manage the VM balloon targets 
independently of xapi.

Does that help at all?

Cheers,
Dave

> Thanks for the link. I'll try to find something useful.
> 
> Best wishes,
> Kakadu
> 
> 
> On Fri, Oct 19, 2012 at 7:27 PM, Dave Scott <Dave.Scott@xxxxxxxxxxxxx>
> wrote:
> >
> > Hi,
> >
> > Kakadu wrote:
> >
> >> Hey.
> >>
> >> I have accepted a challenge about disabling some features of
> >> automatical rebalancing. For example, I want squeezed to raise an
> >> exception while migration in case if there is not enough free memory
> >> and some squeezing needed. So I fixed reserve-memory handler in my
> >> squeezed-like daemon [1] and implemented successful result only when
> >> we can get needed memory without squeezing [2].
> >>
> >> My big problem is testing that stuff. I have vm with these
> >> characteristics
> >> $ xe vm-param-list uuid=ec1dec56-ae4f-d854-8065-e106a1139361 | grep
> >> memory
> >>                  memory-actual ( RO): 250609664
> >>                  memory-target ( RO): 250609664
> >>                memory-overhead ( RO): 4194304
> >>              memory-static-max ( RW): 250000000
> >>             memory-dynamic-max ( RW): 250000000
> >>             memory-dynamic-min ( RW): 250000000
> >>              memory-static-min ( RW): 250000000
> >>
> >> and while localhost migration Squeezer says that it can't  reserve
> >> memory without squeezing.
> >>
> >> [20121019T14:36:28.830Z|debug|xenhost-1|0|reserve_memory(xapi,
> >> 256428)|xenstore-rpc] using new version of reserve_memory
> >> [20121019T14:36:28.830Z|debug|xenhost-1|0|reserve_memory(xapi,
> >> 256428)|xenops] force_change_host_free_memory required_mem = 265644
> >> KiB
> >> [20121019T14:36:28.831Z|debug|xenhost-1|0|reserve_memory(xapi,
> >> 256428)|xenops] Total non-domain reservations = 811008
> >> [20121019T14:36:28.831Z|debug|xenhost-1|0|reserve_memory(xapi,
> >> 256428)|xenops] domid 3 has been declared inactive
> >> [20121019T14:36:28.831Z|debug|xenhost-1|0|reserve_memory(xapi,
> >> 256428)|xenops] total_range = 0 gamma = 1.000000 gamma' = inf
> >> [20121019T14:36:28.831Z|debug|xenhost-1|0|reserve_memory(xapi,
> >> 256428)|xenops] Total additional memory over dynamic_min = 2675808
> >> KiB; will set gamma = 1.00 (leaving unallocated 0 KiB)
> >> [20121019T14:36:28.831Z|debug|xenhost-1|0|reserve_memory(xapi,
> >> 256428)|xenops] Maximum possible free memory if all active domains
> >> balloon down to dynamic_min = 2941452
> >> [20121019T14:36:28.831Z|debug|xenhost-1|0|reserve_memory(xapi,
> >> 256428)|xenops] current host free mem = 2941452 KiB (aiming for
> 265644
> >> KiB); OK; all domain targets not reached; allocation phase
> >> [20121019T14:36:28.831Z|debug|xenhost-1|0|reserve_memory(xapi,
> >> 256428)|xenops] Can't free 265644 KiB: some domains need squeezing
> >>
> >> I'm a little bit confused why first number is less than second in `
> >> mem = 2941452 KiB (aiming for 265644 KiB)`. Maybe I dont understand
> >> something good enough
> >
> > I think what it's trying to say is:
> >
> > The host has 2.9 GiB free but we'd like to give most of this free
> memory away to domains (by 'balancing'), to leave only 265644 KiB left.
> >
> >> So I have two questions:
> >> 1) How to setup parameters for testing migration with my new daemon?
> >> 2) What else pifalls I will have in my way while disabling
> >> autobalancing?
> >
> > When you try to migrate to a host which hasn't got much free memory,
> do you intend to run the existing squeezing logic?
> >
> > BTW there is some internal squeezed design documentation here, just
> in case its useful:
> >
> > https://github.com/xen-org/xen-api/tree/master/docs/squeezed
> >
> > Cheers,
> > Dave
> >
> >>
> >>
> >> Cheers,
> >> Kakadu
> >>
> >> [1] https://github.com/Kakadu/xcp-
> xapi/blob/master/debian/patches/0101-
> >> serred.patch#L123
> >> [2] https://github.com/Kakadu/xcp-
> xapi/blob/master/debian/patches/0101-
> >> serred.patch#L617
> >>
> >> _______________________________________________
> >> Xen-api mailing list
> >> Xen-api@xxxxxxxxxxxxx
> >> http://lists.xen.org/cgi-bin/mailman/listinfo/xen-api

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