* [LSF/MM/BPF TOPIC] Implementing KVM vCPU Priority boosting via BPF
@ 2024-01-24 2:59 Joel Fernandes
2024-01-24 17:15 ` David Vernet
0 siblings, 1 reply; 2+ messages in thread
From: Joel Fernandes @ 2024-01-24 2:59 UTC (permalink / raw)
To: bpf, lsf-pc, David Vernet, Sean Christopherson, Vineeth Pillai,
Steven Rostedt, Suleiman Souhlal
We should discuss a new approach for increasing KVM virtual CPU (vCPU) priority
when guests need low latency. The last RFC posting [1] on this is thought to be
too rigid and baking too much policy into the kernel. Incorporating complex
policy logic directly into KVM seems problematic long-term for maintenance. Lets
discuss leveraging BPF programs to offload more scheduling policy decisions to
BPF / userspace.
Specific issues to discuss:
* Add support for enabling BPF programs to share memory and interface with guest.
* Create a kernel function allowing BPF programs to call sched_setscheduler(),
facilitating priority boosting.
* UAPI concerns.
* Challenges with loading BPF programs in guest userspace we don't control.
[1] https://lore.kernel.org/all/20231214024727.3503870-1-vineeth@bitbyteword.org/
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [LSF/MM/BPF TOPIC] Implementing KVM vCPU Priority boosting via BPF
2024-01-24 2:59 [LSF/MM/BPF TOPIC] Implementing KVM vCPU Priority boosting via BPF Joel Fernandes
@ 2024-01-24 17:15 ` David Vernet
0 siblings, 0 replies; 2+ messages in thread
From: David Vernet @ 2024-01-24 17:15 UTC (permalink / raw)
To: Joel Fernandes
Cc: bpf, lsf-pc, Sean Christopherson, Vineeth Pillai, Steven Rostedt,
Suleiman Souhlal
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On Tue, Jan 23, 2024 at 09:59:50PM -0500, Joel Fernandes wrote:
> We should discuss a new approach for increasing KVM virtual CPU (vCPU) priority
> when guests need low latency. The last RFC posting [1] on this is thought to be
> too rigid and baking too much policy into the kernel. Incorporating complex
> policy logic directly into KVM seems problematic long-term for maintenance. Lets
> discuss leveraging BPF programs to offload more scheduling policy decisions to
> BPF / userspace.
>
> Specific issues to discuss:
>
> * Add support for enabling BPF programs to share memory and interface with guest.
>
> * Create a kernel function allowing BPF programs to call sched_setscheduler(),
> facilitating priority boosting.
>
> * UAPI concerns.
>
> * Challenges with loading BPF programs in guest userspace we don't control.
>
> [1] https://lore.kernel.org/all/20231214024727.3503870-1-vineeth@bitbyteword.org/
+1 to discussing all of the above at LSFMM, ideally as part of the BPF
track.
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