IPMI SOL performance

[Tom Joseph]

On Tuesday 20 March 2018 12:17 AM, Emily Shaffer wrote:
>
>
> On Mon, Mar 19, 2018 at 9:27 AM Stewart Smith 
> <stewart at linux.vnet.ibm.com <mailto:stewart at linux.vnet.ibm.com>> wrote:
>
>     Emily Shaffer <emilyshaffer at google.com
>     <mailto:emilyshaffer at google.com>> writes:
>     >> Is it a possibility to just increase the petitboot timeout? Do
>     you have an
>     > idea of how much we are missing it by?
>
>     Worst case (may be different currently due to improvements in ipmi
>     stack) was about 10-15 minutes.
>
> Yikes.
>
>
>     We have different issues on the SSH console though, we can end up
>     dropping chunks of console output under load (BMC CPU load or high
>     console usage).
>
>     I think Jeremy can relive the trauma of heading into the TTY
>     layer, but
>     I wonder if the solution here has something to do with having a
>     end-to-end flow control story.
>
>     --
>     Stewart Smith
>     OPAL Architect, IBM.
>
>
> I was looking in the spec and I saw that the packet length for SOL is 
> configurable in the session header, but I didn't find the layout for 
> the header.  It's definitely not configurable past 255B?

Even though character data field is a variable length field, the 
accepted character count in the SOL payload is a single byte. It is 
based on the accepted character count that console acknowledges to BMC 
and offset is changed. That is the 255 character limitation mentioned.
>
> It really doesn't sound like IPMI is well-suited to this task.  Tom, 
> can you post a proposal for the OEM command you'd like to see, or if 
> you've tried one internally?
I haven't tried this option, the OEM option is to bump the accepted 
character count field. It will need changes on the clients (like ipmitool).

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