Messages in this thread | | | Date | Wed, 16 Nov 2022 08:52:28 +0800 | Subject | Re: [RFC 0/4] pci/sriov: support VFs dynamic addition | From | "Longpeng (Mike, Cloud Infrastructure Service Product Dept.)" <> |
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Hi Oliver,
在 2022/11/15 10:06, Oliver O'Halloran 写道: > On Tue, Nov 15, 2022 at 1:08 AM Longpeng (Mike, Cloud Infrastructure > Service Product Dept.) <longpeng2@huawei.com> wrote: >> >> *snip* >> >> Adding 2K+ VFs to the sysfs need too much time. >> >> Look at the bottomhalf of the hypervisor live update: >> kexec --> add 2K VFs --> restore VMs >> >> The downtime can be reduced if the sequence is: >> kexec --> add 100 VFs(the VMs used) --> resotre VMs --> add 1.9K VFs > > Right, so you want to add VFs in batches rather than all at once. > Personally I think the bitmap approach is error prone since it renders > the meaning of pf_dev->sriov->num_VFs unclear and there's some hairy > code in arch/powerpc/ that approach will likely break. A better
I ran a quick search in the arch/powerpc/, do you mean the pseries_call_allow_unfreeze ? Or would you please point the code?
> approach would be to add an attribute to control the number of VFs > enabled in hardware and allowing sriov_numvfs to accept any number > between the current value and sriov_hw_numvfs. e.g. your HV setup
Oh, this is a constructive suggestion, I'll try in the next step.
> would look something like: > > echo 2048 > sriov_hw_numvfs > echo 100 > sriov_numvfs > It's fixed to add the first 100 VFs first, maybe providing an interface that users can specify which id or which range of ids to be added first would be better?
> # time passes > echo 2048 > sriov_numvfs > > This would be fairly simple to implement and you can make it backwards > compatible by having writes to sriov_numvfs retain their current > semantics if sriov_hw_numvfs is zero. > .
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