[patch] IPMI KCS can drop the lock while servicing a request

Alexander V. Chernikov melifaro at FreeBSD.org
Sun Mar 24 22:38:52 UTC 2013

On 24.03.2013 07:11, Eric van Gyzen wrote:
> At work, we discovered that our application's IPMI thread would often
> use a lot of CPU time. The KCS thread uses DELAY to wait for the BMC, so
> it can run without sleeping for a "long" time with a slow BMC. It also
> holds the ipmi_softc.ipmi_lock during this time. When using adaptive
> mutexes, an application thread that wants to operate on the
> ipmi_pending_requests list will also spin during this same time.
We suffer from the same problem, too.
> We see no reason that the KCS thread needs to hold the lock while
> servicing a request. We've been running with the attached patch for a
Well, this seems to be true. I'll try to commit something like this 
patch in several days.

> few months, with no ill effects.
> Eric
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