Re: [Qemu-devel] RDMA: please pull and re-test freezing fixes

[Michael R. Hines]

These are great results. Even the one that doesn't converge is good,
because it shows that your patch for CPU throttling earlier on the
mailing list is still very necessary.

Thanks a lot, I will send out a V10 patch to everybody's results.

- Michael

Would you be interested in me posting them to the wiki?

On 6/14/2013 1:38 PM, Michael R. Hines wrote:
> Chegu,
>
> I sent a V9 to the mailing list:
>
> The version goes even further, by explicitly timing the pinning
> latency and
> pushing the value out to QMP so the user clearly knows which component
> of total migration time is consumed by pinning.
>
> If you're satisfied, I'd appreciate if I could add your Reviewed-By: =)
>


Pl. see below...and yes you can add me.
Thanks,
Vinod



The migration speed was set to 40G and the downtime to 2sec for all 
experiments
below.

Note: Idle guests are not interesting due to tons of zero pages etc...but
including them here to highlght the overhead of pinning.

1) 20vcpu/64GB guest: (kind of a larger sized Cloud-type guest)

a) Idle guest with No pinning (default) :

capabilities: xbzrle: off x-rdma-pin-all: off
Migration status: completed
total time: 51062 milliseconds
downtime: 1948 milliseconds
pin-all: 0 milliseconds
transferred ram: 1816547 kbytes
throughput: 6872.23 mbps
remaining ram: 0 kbytes
total ram: 67117632 kbytes
duplicate: 16331552 pages
skipped: 0 pages
normal: 450038 pages
normal bytes: 1800152 kbytes


b) Idle guest with Pinning :

capabilities: xbzrle: off x-rdma-pin-all: on
Migration status: completed
total time: 47451 milliseconds
downtime: 2639 milliseconds
pin-all: 22780 milliseconds
transferred ram: 67136643 kbytes
throughput: 25222.91 mbps
remaining ram: 0 kbytes
total ram: 67117632 kbytes
duplicate: 0 pages
skipped: 0 pages
normal: 16780064 pages
normal bytes: 67120256 kbytes

There weere no freezes observed in the guest at the start of the migration
but the qemu monitor prompt was not responsive for the duration of the
memory pinning.

Total migration time was affected by the cost pinning at the start of the
migration as shown above( This issue can be pursued and optimized later).

c) Pining + guest running a Java warehouse workload (I cranked the 
workload up
                                         to keep the guest 95+% busy)

capabilities: xbzrle: off x-rdma-pin-all: on
Migration status: active
total time: 412706 milliseconds
expected downtime: 499 milliseconds
pin-all: 22758 milliseconds
transferred ram: 657243669 kbytes
throughput: 25241.89 mbps
remaining ram: 7281848 kbytes
total ram: 67117632 kbytes
duplicate: 0 pages
skipped: 0 pages
normal: 164270810 pages
normal bytes: 657083240 kbytes
dirty pages rate: 369925 pages

No Convergence ! (For workloads where the memory dirty rate is very high
there are other alternatives that have been discussed in the past...)

---

Enterprise type guests tend to get fatter (more memory per cpu) than the
larger Cloud  guests...so here are a coupld of them.


a) 20VCPU/256G Idle guest :

Default:

capabilities: xbzrle: off x-rdma-pin-all: off
Migration status: completed
total time: 259259 milliseconds
downtime: 3924 milliseconds
pin-all: 0 milliseconds
transferred ram: 5522078 kbytes
throughput: 6586.06 mbps
remaining ram: 0 kbytes
total ram: 268444224 kbytes
duplicate: 65755168 pages
skipped: 0 pages
normal: 1364124 pages
normal bytes: 5456496 kbytes


Pinned:

capabilities: xbzrle: off x-rdma-pin-all: on
Migration status: completed
total time: 219053 milliseconds
downtime: 4277 milliseconds
pin-all: 118153 milliseconds
transferred ram: 268512809 kbytes
throughput: 22209.32 mbps
remaining ram: 0 kbytes
total ram: 268444224 kbytes
duplicate: 0 pages
skipped: 0 pages
normal: 67111817 pages
normal bytes: 268447268 kbytes


b) 40VCPU/512GB Idle guest :


Default:

capabilities: xbzrle: off x-rdma-pin-all: off
Migration status: completed
total time: 670577 milliseconds
downtime: 6139 milliseconds
pin-all: 0 milliseconds
transferred ram: 10279256 kbytes
throughput: 6150.93 mbps
remaining ram: 0 kbytes
total ram: 536879680 kbytes
duplicate: 131704099 pages
skipped: 0 pages
normal: 2537017 pages
normal bytes: 10148068 kbytes

Pinned:

capabilities: xbzrle: off x-rdma-pin-all: on
Migration status: completed
total time: 527576 milliseconds
downtime: 6314 milliseconds
pin-all: 312984 milliseconds
transferred ram: 537129685 kbytes
throughput: 20177.27 mbps
remaining ram: 0 kbytes
total ram: 536879680 kbytes
duplicate: 0 pages
skipped: 0 pages
normal: 134249644 pages
normal bytes: 536998576 kbytes

No freezes in the guest due to memory pinning. (Freezes were only due to 
the
dirty bitmap synchup stuff which is being done while BQL is held. Juan is
working on addresing already for qemu 1.6)

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