Re: MSI interrupts

On Tue, 25 Mar 2025 22:19:07 +0000, Dan Cross wrote:

In article <e4ecfb53ef4f33f10b6d2548d5930159@www.novabbs.org>,
MitchAlsup1 <mitchalsup@aol.com> wrote:
>

Your stuff sounds fine for getting into the critsec; but it
doesn't help you once you're in it, and it seems like it may
hurt you if some higher-priority thing comes along and yanks
your lock out from under you.

>
I conceded that point at least 2 days ago.

>
Ok, now we're back to the question then: what purpose does it
serve?

You (well Chris) can write critical sections where a low priority
holder can give way to the higher priority requestor such that
the low priority holder reverts back to before it entered CS,
and does not see the lock being stolen.
For the sizes of CSs this covers--it prevent priority inversion.

       It doesn't seem like it can be usefully applied to
anything other than building traditional mutexes based on spin
locks, and even then I'm not sure if that's correct (see above).

And here I thought you had an imagination .....

- Dan C.