Re: [PATCH] BPF: Disable on PREEMPT_RT

Thomas Gleixner
2019-10-18T08:38:13Z

On Thu, 17 Oct 2019, David Miller wrote:

> From: Clark Williams <williams@redhat.com>
> Date: Thu, 17 Oct 2019 21:49:17 -0500
>
> > BPF programs cannot loop and are limited to 4096 instructions.
>
> The limit was increased to 1 million not too long ago.

Assuming a instruction/cycle ratio of 1.0 and a CPU frequency of 2GHz,
that's 500us of preempt disabled time. Out of bounds by at least one order
of magntiude for a lot of RT scenarios.

Thanks,

tglx