Re: [RFC] Add BPF_PROG_TYPE_CGROUP_IOCTL

From: Daniel Vetter <daniel@ffwll.ch>
To: Kenny Ho <y2kenny@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Dave Airlie <airlied@gmail.com>, Kenny Ho <Kenny.Ho@amd.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@chromium.org>, bpf <bpf@vger.kernel.org>,
	Network Development <netdev@vger.kernel.org>,
	Linux-Fsdevel <linux-fsdevel@vger.kernel.org>,
	"open list:CONTROL GROUP (CGROUP)" <cgroups@vger.kernel.org>,
	Alex Deucher <alexander.deucher@amd.com>,
	amd-gfx list <amd-gfx@lists.freedesktop.org>,
	DRI Development <dri-devel@lists.freedesktop.org>,
	Brian Welty <brian.welty@intel.com>
Subject: Re: [RFC] Add BPF_PROG_TYPE_CGROUP_IOCTL
Date: Fri, 7 May 2021 10:59:38 +0200	[thread overview]
Message-ID: <YJUBer3wWKSAeXe7@phenom.ffwll.local> (raw)
In-Reply-To: <CAOWid-fL0=OM2XiOH+NFgn_e2L4Yx8sXA-+HicUb9bzhP0t8Bw@mail.gmail.com>

On Thu, May 06, 2021 at 10:06:32PM -0400, Kenny Ho wrote:
> Sorry for the late reply (I have been working on other stuff.)
> 
> On Fri, Feb 5, 2021 at 8:49 AM Daniel Vetter <daniel@ffwll.ch> wrote:
> >
> > So I agree that on one side CU mask can be used for low-level quality
> > of service guarantees (like the CLOS cache stuff on intel cpus as an
> > example), and that's going to be rather hw specific no matter what.
> >
> > But my understanding of AMD's plans here is that CU mask is the only
> > thing you'll have to partition gpu usage in a multi-tenant environment
> > - whether that's cloud or also whether that's containing apps to make
> > sure the compositor can still draw the desktop (except for fullscreen
> > ofc) doesn't really matter I think.
> This is not correct.  Even in the original cgroup proposal, it
> supports both mask and count as a way to define unit(s) of sub-device.
> For AMD, we already have SRIOV that supports GPU partitioning in a
> time-sliced-of-a-whole-GPU fashion.

Hm I missed that. I feel like time-sliced-of-a-whole gpu is the easier gpu
cgroups controler to get started, since it's much closer to other cgroups
that control bandwidth of some kind. Whether it's i/o bandwidth or compute
bandwidht is kinda a wash.

CU mask feels a lot more like an isolation/guaranteed forward progress
kind of thing, and I suspect that's always going to be a lot more gpu hw
specific than anything we can reasonably put into a general cgroups
controller.

Also for the time slice cgroups thing, can you pls give me pointers to
these old patches that had it, and how it's done? I very obviously missed
that part.

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch