Changing mfi max_cmds for new tbolt based cards?

[Steven Hartland]

I've been doing a lot of work over the past few weeks find and fixing bugs
in the mfi driver. One of these fixes was to ensure that mfi_max_cmds is
used consistently throughout the driver to ensure validation checks work
as expected.

During this I noticed that mfi_max_cmds is very low for current generation
controllers. In my case 2208 based controller reports 1008 cmd slots, so
quite a jump from the previous max which I believe was 256?

I was wondering if we should look to change the how our sysctl is setup?

Recently John you made the following comment:
> Mess with mfi_max_cmds at your own risk.  The limit was added to work around
> broken mfi(4) firmware revisions that would lock up when the entire command
> queue (256) was used.  Just a suggestion to be cautious.  It is probably
> safe to use more than 128, but I would be wary of using all of the slots on 
> your adapter.  (A verbose boost will show you the number of command slots your
> firmware supports.)
> http://lists.freebsd.org/pipermail/freebsd-current/2012-September/036639.html

Do you have an information about this specifically:-
1. Which generation of controller?
2. Which controller firmware was effected?
3. Was there a reproducible scenario which triggered this behaviour?

I'm going to test stability here but my current thinking is to change the
default to -1 (controller limit) for new tbolt based controllers.

N.B. Resent from correct list account, sorry for the duplicate John.

    Regards
    Steve

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