[libvirt] question about rdma migration

Roy Shterman roysh at mellanox.com
Tue Mar 22 16:50:40 UTC 2016


On 3/22/2016 3:58 PM, Jiri Denemark wrote:
> On Tue, Mar 22, 2016 at 13:16:49 +0000, Roy Shterman wrote:
>> OK, I will describe it better,
>>
>> I'm developing iSER transport option inside libiscsi, as part of that I'm planning to implement it also in QEMU block layer.
>>
>> iSER RDMA components (QP, CQ, MR) need to lock some amount of memory (predictable amount),
>>
>> So, needed memory to be locked is (num of libiscsi-iser devices in VM)*(constant amount per device),
> Well, it should be easy enough to compute and automatically set the
> limit from libvirt then. Unless the "constant amount per device" changes
> anytime someone touches the code in QEMU or libiscsi.

Yes, it should be constant

>
>> For now, I'm using locked option in libvirt, although I don't really need to lock all VM memory.
> For testing you could perhaps try playing with hooks and prlimit, but
> forcing libvirt to lock all memory is still easier.

tried with setrlimit inside QEMU without any success.
 I'm working with libvirt package from redhat 7.0, so like you said locking all memory was the easiest choice for me.

I'm not familiar with libvirt code, where do you suggest I will add the calculation and setting?
>
> Jirka

Regards,
Roy




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