On 5/6/24 16:34, Przemek Kitszel wrote:
On 4/30/24 03:59, Jakub Kicinski wrote:
On Fri, 26 Apr 2024 15:22:02 +0200 Przemek Kitszel wrote:
## devlink resources (with current API)
`devlink resource` is compelling, partially given the name sounds like a
perfect match. But when we dig just a little bit, the current Path+sizes
(min,max,step) is totally off to what is the most elegant picture of the
situation. In order to fit into existing uAPI, I would need to register
VFs as PF's resource, then GLOBAL LUT and PF LUT as a sub resource to
that (each VF gets two entries under it; plus two additional ones for
PF) I don't like it, I also feel like there is not that much use of
current resources API (it's not natural to use it for distribution, only
for limitation).
Can you share more on how that would look like?
something like below (though I have added one more layer to illustrate
broader idea, it could be chopped down)
[1]
From the description it does not sound so bad. Maybe with some CLI / UI
changes it will be fine?
## devlink resources (with extended API)
It is possible to extend current `devlink resource` so instead of only
Path+size, there would be also Path+Owner option to use.
The default state for ice driver would be that PFs owns PF LUTs, GLOBAL
LUTs are all free.
example proposed flow to assign a GLOBAL LUT to VF0 and PF LUT to VF1:
pf=0000:03:00.0 # likely more meaningful than VSI idx, but open for
vf0=0000:03:00.1 # suggestions
vf1=0000:03:00.2
devlink resource set pci/$pf path /lut/lut_table_512 owner $pf
devlink resource set pci/$pf path /lut/lut_table_2048 owner free
devlink resource set pci/$pf path /lut/lut_table_512 owner $vf0
devlink resource set pci/$pf path /lut/lut_table_2048 owner $vf1
Don't we want some level of over-subscription to be allowed?
In theory we could reuse/share tables, especially with the case of auto
filled ones, not sure if I would want to implement that with the very
first series, but good point to design interface with that in mind.
To move in this direction we could make numbered LUTs an entity that is
set/show'ed (digression: this would feel more like mmap() than malloc())
(The imaginary output below does not do that).
The main problem with the [1] above for "current API" for me is lack of
aggregate device [2] in the structures represented by devlink. Let me
show what it would be with one more layer (so I put PFs under that, and
VFs one layer down).
Here is an example with 2 PFs, one of with with 3 VFs, each of them with
different LUT
$ devlink resource show $device
$device:
name lut size 4 unit entry
resources:
name lut_table_2048 size 2 unit entry size_min 0 size_max 8
size_gran 1
name lut_table_512 size 2 unit entry size_min 0 size_max 16
size_gran 1
name functions size 5 unit entry
resources:
name pf0
resources:
name lut_table_2048 size 0 size_max 1 ...
name lut_table_512 size 1 size_max 1 ...
name vf0
resources:
name lut_table_2048 size 1 size_max 1 ...
name lut_table_512 size 0 size_max 1 ...
name vf1
resources:
name lut_table_2048 size 0 size_max 1 ...
name lut_table_512 size 1 size_max 1 ...
name vf2
resources:
name lut_table_2048 size 0 size_max 1 ...
name lut_table_512 size 0 size_max 1 ...
name pf1
resources:
name lut_table_2048 size 1 ...
name lut_table_512 size 0 ...
where $device stands for the aggregate device (covers 8 PFs in case of
8-port split used)
As of now I started playing with that so I have an aggregate devlink
instance, but it is registered for the very same struct device as PF0.
So that presents an issue for user trying to show only PF0, but output
shows all the data (otherwise there would be no option to show
all of it)
Assigning resources will be easier as aggregate device could simply
disallow it, but it is similar.
Perhaps some userspace devlink tweak would resolve that, but would it be
nice to have different devlink handle (without creating a dummy PCI
device).
Any advice how to make it distinguished?
(IOW: give my aggregate/whole device a different name that any PF)
Please find below what I have now in terms of nesting (doubled device
addresses are easy to spot):
iproute2 $ ./devlink/devlink dev
pci/0000:18:00.0 # PF0, as I devlink_register() both PFs and whole-dev
pci/0000:18:00.0: # whole-dev one
nested_devlink:
pci/0000:18:00.0 # PF0
pci/0000:af:00.0
pci/0000:af:00.0:
nested_devlink:
pci/0000:af:00.0
pci/0000:af:00.1
pci/0000:af:00.2
pci/0000:af:00.3
pci/0000:af:00.4
pci/0000:af:00.5
pci/0000:af:00.6
pci/0000:af:00.7
pci/0000:af:00.1
pci/0000:af:00.2
pci/0000:af:00.3
pci/0000:af:00.4
pci/0000:af:00.5
pci/0000:af:00.6
pci/0000:af:00.7
and all named PF/VFs in the output would need "dummy" size calculations
(I would like to remove this need though)
When all resources are assigned, all "size 0" entries should have also
"size_max 0" to indicate no room for growth.
[2] aggregate device discussion:
https://lore.kernel.org/intel-wired-lan/cfe84890-f999-4b97-a012-6f9fd16da...@intel.com/
