IPMI SOL performance

[Emily Shaffer]

On Mon, Mar 19, 2018 at 4:18 AM Tom Joseph <tomjose at linux.vnet.ibm.com>
wrote:

>
>    Related issue -  https://github.com/openbmc/openbmc/issues/2958
>
> On Monday 19 March 2018 04:43 PM, Tom Joseph wrote:
> > Hello,
> >
> > I wanted to discuss about an issue related to IPMI SOL. Petitboot has
> > a menu to select the boot option, it has a timeout after which the
> > default boot option is selected and boot continues.The observation is
> > that when verbose debug traces are enabled in the hostboot, by the
> > time petitboot options are printed on the SOL console the menu timeout
> > expires and the user is not able to change the boot option.
> >
> > The same issue is not hit by the ssh console on port 2200 and does not
> > miss the timeout of the petitboot menu option.
> >
> > IPMI uses UDP protocol and the maximum size of the  SOL payload per
> > packet according to the specification is 255 bytes. Also the ack for
> > each of the IPMI packet requires a command lookup
> > and execution. Compared with IPMI SOL, ssh supports 64kb payloads and
> > ack does not need an application lookup, so the round-trip timing is
> > faster. IPMI specification for SOL is written with UART speed as
> > reference, but the VUART pushes the data at a much faster rate.
> >
> > One suggestion that I came across support an OEM payload size for SOL,
> > which is higher than 255 bytes, to get a better throughput. Please do
> > share other ideas to tackle this problem and improve performance.
> >
> > Regards,
> > Tom
> >
>
> Is it a possibility to just increase the petitboot timeout? Do you have an
idea of how much we are missing it by?
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