Re: [dpdk-dev] [PATCH 0/8] eBPF arm64 JIT support

[Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>]

Adding Arm JIT and Kernel experts

> -----Original Message-----
> From: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> Sent: Thursday, October 3, 2019 10:06 AM
> To: Jerin Jacob <jerinjacobk@gmail.com>; thomas@monjalon.net
> Cc: jerinj@marvell.com; dpdk-dev <dev@dpdk.org>; Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com>; Gavin Hu (Arm Technology China)
> <Gavin.Hu@arm.com>
> Subject: RE: [dpdk-dev] [PATCH 0/8] eBPF arm64 JIT support
> 
> Hi everyone,
> 
> >
> > On Thu, Oct 3, 2019 at 6:21 PM Thomas Monjalon <thomas@monjalon.net>
> wrote:
> > >
> > > 03/09/2019 12:59, jerinj@marvell.com:
> > > > Added eBPF arm64 JIT support to improve the eBPF program
> > > > performance on arm64.
> > > >
> > > >  lib/librte_bpf/bpf_jit_arm64.c         | 1451 ++++++++++++++++++++++++
> > >
> > > I am concerned about duplicating the BPF JIT effort in DPDK and Linux.
> > > Could we try to pull the Linux JIT?
> > > Is the license the only issue?
> >
> > That's one issue.
> >
> > >
> > > After a quick discussion, it seems the Linux authors are OK to
> > > arrange their JIT code for sharing with userspace projects.
> >
> > I did a clean room implementation considering some optimization for
> > DPDK etc(Like if stack is not used then don't push stack etc) and
> > wherever Linux can be improved, I have submitted the patch also to
> > Linux as well.(Some more pending as well)
> >
> >
> https://github.com/torvalds/linux/commit/504792e07a44844f24e9d79913e
> 4a
> > 2f8373cd332
> >
> > And Linux has a framework for instruction generation for debugging
> > etc. So We can not copy and paste the code from Linux as is.
> >
> > My view to keep a different code base optimize for DPDK use cases and
> > library requirements(for example, tail call is not supported in DPDK).
> > For arm64/x86 case the code is done so it is not worth sync with
> > Linux. For new architecture, it can be if possible.
> >
> > Konstantin,
> > Your thoughts?
> >
> 
> My thought would be that if we have JIT eBPF compiler already in DPDK for
> one arch (x86) there is absolutely no reason why we shouldn't allow it for
> different arch (arm).
> About having a common code-base with Linux eBPF JITs implementation - I
> think it is a very good idea, but I don’t' think it could be achieved without
> significant effort.
> DPDK and Linux JIT code-generators differ quite a bit.
> So my suggestion - let's go ahead and integrate Jerin patch into 19.11,
> meanwhile start talking with linux guys how common JIT code-base could be
> achieved.
> Konstantin
> 
> 
>