RE: [PATCH] Abstracted Priority Inheritance for RT

From: Sven Dietrich
Date: Thu Jun 02 2005 - 20:12:13 EST



>
> On Thu, Jun 02, 2005 at 01:43:54AM -0400, john cooper wrote:
> > That might have been me. The last time I looked at this
> specifically,
> > full transitive promotion was being done in the RT patch. However
> > unlike your attempt at scaling the lock scope, the RT patch had one
> > lock which coordinated all mutex dependency traversals
> system wide.
> > This lock must be speculatively acquired even before we ascertain
> > transitive promotion is required.
> >
> > So it doesn't scale as well as it could in the case of
> > large count SMP systems. The response was that of "get
> > it to work first and then we'll get it to scale" which
> > is reasonable.
>
> Just curious, what do you thinks about the rw-lock comments
> from Esben in that a real rw-lock can't be deterministic ?
>

I think it can be deterministic if the number of readers is limited (to 1)

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