Re: [PATCH v2 0/3] devlink region trigger support

From: Jiri Pirko <jiri@resnulli.us>
To: Yunsheng Lin <linyunsheng@huawei.com>
Cc: Jacob Keller <jacob.e.keller@intel.com>,
	netdev@vger.kernel.org, valex@mellanox.com
Subject: Re: [PATCH v2 0/3] devlink region trigger support
Date: Mon, 13 Jan 2020 17:58:58 +0100	[thread overview]
Message-ID: <20200113165858.GG2131@nanopsycho> (raw)
In-Reply-To: <fe6c0d5e-5705-1118-1a71-80bd0e26a97e@huawei.com>

Sat, Jan 11, 2020 at 02:51:00AM CET, linyunsheng@huawei.com wrote:
>On 2020/1/11 1:52, Jacob Keller wrote:
>> On 1/9/2020 8:10 PM, Yunsheng Lin wrote:
>>> On 2020/1/10 3:33, Jacob Keller wrote:
>>>> This series consists of patches to enable devlink to request a snapshot via
>>>> a new DEVLINK_CMD_REGION_TRIGGER_SNAPSHOT.
>>>>
>>>> A reviewer might notice that the devlink health API already has such support
>>>> for handling a similar case. However, the health API does not make sense in
>>>> cases where the data is not related to an error condition.
>>>
>>> Maybe we need to specify the usecases for the region trigger as suggested by
>>> Jacob.
>>>
>>> For example, the orginal usecase is to expose some set of flash/NVM contents.
>>> But can it be used to dump the register of the bar space? or some binary
>>> table in the hardware to debug some error that is not detected by hw?
>>>
>> 
>> 
>> regions can essentially be used to dump arbitrary addressable content. I
>> think all of the above are great examples.
>> 
>> I have a series of patches to update and convert the devlink
>> documentation, and I do provide some further detail in the new
>> devlink-region.rst file.
>> 
>> Perhaps you could review that and provide suggestions on what would make
>> sense to add there?
>
>For the case of region for mlx4, I am not sure it worths the effort to
>document it, because Jiri has mention that there was plan to convert mlx4 to
>use "devlink health" api for the above case.

It is on the TODO list, yes. For mlx4 usecase the healh reporters are
more suitable.

>
>Also, there is dpipe, health and region api:
>For health and region, they seems similar to me, and the non-essential
>difference is:
>1. health can be used used to dump content of tlv style, and can be triggered
>   by driver automatically or by user manually.
>
>2. region can be used to dump binary content and can be triggered by driver
>   automatically only.
>
>It would be good to merged the above to the same api(perhaps merge the binary
>content dumping of region api to health api), then we can resue the same dump
>ops for both driver and user triggering case.

I was thinking about that as well. Will check it out.

>
>For dpipe, it does not seems flexible enough to dump a table, yes, it provides

Why? That is the purpose of the dpipe, but make the hw
pipeline visible and show you the content of individual nodes.

>better visibility, but I am not sure it worth the effort, also, it would be better
>to share the same table dump ops for driver and user triggering case.
>For hns3 driver, we may have mac, vlan and flow director table that may need to dump
>in both driver and user triggering case to debug some complex issues.
>
>So It would be better to be able to dump table(maybe including binary table), binary
>content and tlv content for a sinle api, I suppose the health api is the one to do
>that? because health api has already supported driver and user triggering case, and
>only need to add the table and binary content dumpping.
>
>
>> 
>> https://lore.kernel.org/netdev/20200109224625.1470433-13-jacob.e.keller@intel.com/
>> 
>> Thanks,
>> Jake
>> 
>> .
>> 
>