On 10/10/17 22:28, Jonathan Cameron wrote:
Hi All,
Please forward this email to anyone you think may be interested.
Have forwarded this to a number of relevant IBMers.
On behalf of Huawei, I am looking into options to foster a wider community
around the various ongoing projects related to Accelerator support within
Linux. The particular area of interest to Huawei is that of harnessing
accelerators from userspace, but in a collaborative way with the kernel
still able to make efficient use of them, where appropriate.
We are keen to foster a wider community than one just focused on
our own current technology. This is a field with no clear answers, so the
widest possible range of input is needed!
The address list of this email is drawn from people we have had discussions
with or who have been suggested in response to Kenneth Lee's wrapdrive
presentation at Linaro Connect and earlier presentations on the more general
issue. A few relevant lists added to hopefully catch anyone we missed.
My apologies to anyone who got swept up in this and isn't interested!
Here we are defining accelerators fairly broadly - suggestions for a better
term are also welcome.
The infrastructure may be appropriate for:
* Traditional offload engines - cryptography, compression and similar
* Upcoming AI accelerators
* ODP type requirements for access to elements of networking
* Systems utilizing SVM including CCIX and other cache coherent buses
* Many things we haven't thought of yet...
As I see it, there are several aspects to this:
1) Kernel drivers for accelerators themselves.
* Traditional drivers such as crypto etc
- These already have their own communities. The main
focus of such work will always be through them.
- What a more general community could add here would be an
overview of the shared infrastructure of such devices.
This is particularly true around VFIO based (or similar)
userspace interfaces with a non trivial userspace component.
* How to support new types of accelerator?
2) The need for lightweight access paths from userspace that 'play well' and
share resources etc with standard in-kernel drivers. This is the area
that Kenneth Lee and Huawei have been focusing on with their wrapdrive
effort. We know there are other similar efforts going on in other companies.
* This may involve interacting with existing kernel communities such as
those around VFIO and mdev.
* Resource management when we may have many consumers - not all hardware
has appropriate features to deal with this.
3) Usecases for accelerators. e.g.
* kTLS
* Storage encryption
* ODP - networking dataplane
* AI toolkits
Discussions we want to get started include:
* A wider range of hardware than we are currently considering. What makes
sense to target / what hardware do people have they would like to support?
* Upstream paths - potential blockers and how to overcome them. The standard
kernel drivers should be fairly straightforward, but once we start looking at
systems with a heavier userspace component, things will get more
controversial!
* Fostering stronger userspace communities to allow these these accelerators
to be easily harnessed.
So as ever with a linux community focusing on a particular topic, the
obvious solution is a mailing list. There are a number of options on how
do this.
1) Ask one of the industry bodies to host? Who?
2) Put together a compelling argument for linux-accelerators@xxxxxxxxxxxxxxx
as probably the most generic location for such a list.
Happy to offer linux-accelerators@xxxxxxxxxxxxxxxx, which I can get set
up immediately (and if we want patchwork, patchwork.ozlabs.org is
available as always, no matter where the list is hosted).
More open questions are
1) Scope?
* Would anyone ever use such an overarching list?
* Are we better off with the usual adhoc list of 'interested parties' + lkml?
* Do we actually need to define the full scope - are we better with a vague
definition?
I think a list with a broad and vaguely defined scope is a good idea -
it would certainly be helpful to us to be able to follow what other
contributors are doing that could be relevant to our CAPI and OpenCAPI work.
2) Is there an existing community we can use to discuss these issues?
(beyond the obvious firehose of LKML).
3) Who else to approach for input on these general questions?
In parallel to this there are elements such as git / patchwork etc but
they can all be done as they are needed.
Thanks
--
Jonathan Cameron
Huawei
--
Andrew Donnellan OzLabs, ADL Canberra
andrew.donnellan@xxxxxxxxxxx IBM Australia Limited
