On Tue, Dec 21, 2021 at 08:41:47AM +0800, Zhouyi Zhou wrote:
> Thanks Paul and Akira for correcting me and helping me (who needs to
> be improved ;-)) make progress
>
> On Tue, Dec 21, 2021 at 7:39 AM Paul E. McKenney <paulmck@xxxxxxxxxx> wrote:
> >
> > On Tue, Dec 21, 2021 at 06:42:04AM +0800, Zhouyi Zhou wrote:
> > > Thanks Paul and Akira
> > >
> > > great improvement to perfbook's glossary!
> > >
> > > A question below ;-)
> > >
> > > On Tue, Dec 21, 2021 at 4:15 AM Paul E. McKenney <paulmck@xxxxxxxxxx> wrote:
> > > >
> > > > On Mon, Dec 20, 2021 at 06:55:36PM +0900, Akira Yokosawa wrote:
> > > > > Hi Paul,
> > > > >
> > > > > While reading through Section 9.5.4, I noticed a few terms
> > > > > I'd like to see in perfbook's Glossary.
> > > > >
> > > > > - Reference Counter/Counting
> > > > > - Existence Guarantee
> > > > > - Type-safe Memory
> > > > >
> > > > > "Reference counter" is already mentioned in a couple of existing
> > > > > items in the glossary.
> > > > >
> > > > > "Existing guarantee" might be obvious enough and not worthy
> > > > > to be in the glossary.
> > > > >
> > > > > Thoughts?
> > > > >
> > > > > There were only a few minor nits in the section.
> > > > > Will post a patch taking care of them.
> > > >
> > > > Thank you for looking it over! Please see below for a proposed patch
> > > > to the glossary. Oh, and thank you for the checking utilities, very
> > > > nice to get explicit messages rather than subtlely broken formatting!!!
> > > >
> > > > utilities/punctcheck.sh
> > > > ./glossary.tex:547: Type-safe memory\cite{Cheriton96a} is provided by a
> > > > utilities/cleverefcheck.sh
> > > >
> > > > Thanx, Paul
> > > >
> > > > ------------------------------------------------------------------------
> > > >
> > > > commit a8f5948a1b8921941bf4039e278aa7929f64c322
> > > > Author: Paul E. McKenney <paulmck@xxxxxxxxxx>
> > > > Date: Mon Dec 20 09:41:55 2021 -0800
> > > >
> > > > glossary: Add reference count, existence guarantee, and TSM
> > > >
> > > > Where "TSM" is type-safe memory.
> > > >
> > > > Reported-by: Akira Yokosawa <akiyks@xxxxxxxxx>
> > > > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> > > >
> > > > diff --git a/glossary.tex b/glossary.tex
> > > > index be10f703..31c09232 100644
> > > > --- a/glossary.tex
> > > > +++ b/glossary.tex
> > > > @@ -199,6 +199,14 @@
> > > > increase the overall cost of the computation, resulting in
> > > > linear speedups as threads are added (assuming sufficient
> > > > CPUs are available).
> > > > +\item[\IX{Existence Guarantee}:]
> > > > + An existence guarantee is provided by a synchronization mechanism
> > > > + that prevents a given dynamically allocated object from being
> > > > + freed for the duration of that guarantee.
> > > > + For example, RCU provides existence guarantees for the duration
> > > > + of RCU read-side critical sections.
> > > > + A similar but strictly weaker guarantee is provided by
> > > > + type-safe memory.
> > > here type-safe memory is called 'weaker'
> >
> > Type-safe memory is weaker than existence guarantees ...
> >
> > > > \item[\IXh{Exclusive}{Lock}:]
> > > > An exclusive lock is a mutual-exclusion mechanism that
> > > > permits only one thread at a time into the
> > > > @@ -469,6 +477,11 @@
> > > > A situation in which getting the correct result is not sufficient,
> > > > but where this result must also be obtained within a given amount
> > > > of time.
> > > > +\item[\IX{Reference Count}:]
> > > > + A counter that tracks the number of users of a given object or
> > > > + entity.
> > > > + Reference counters provide existence guarantees and are sometimes
> > > > + used to implement garbage collectors.
> > > > \item[\IX{Scalability}:]
> > > > A measure of how effectively a given system is able to utilize
> > > > additional resources.
> > > > @@ -531,6 +544,17 @@
> > > > A synchronization mechanism that gathers groups of memory
> > > > accesses so as to execute them atomically from the viewpoint
> > > > of transactions on other CPUs or threads.
> > > > +\item[\IX{Type-Safe Memory}:]
> > > > + Type-safe memory~\cite{Cheriton96a} is provided by a
> > > > + synchronization mechanism that prevents a given dynamically
> > > > + allocated object from changing to an incompatible type.
> > > > + Note that the object might well be freed and then reallocated, but
> > > > + the reallocated object is guaranteed to be of a compatible type.
> > > > + Within the Linux kernel, type-safe memory is provided within
> > > > + RCU read-side critical sections for memory allocated from slabs
> > > > + marked with the \co{SLAB_TYPESAFE_BY_RCU} flag.
> > > > + The strictly stronger existence guarantee also prevents freeing
> > > > + of the protected object.
> > >
> > > but why do we use "stronger" here (should not it be "weaker"?)
> >
> > ... Or, alternatively but equivalently, existence guarantees are stronger
> > than type-safe memory.
> >
> > Is there a better way to word this?
> How about this:
>
> It is to note that existence guarantees are stronger than type-safe
> memory and.a strictly stronger existence guarantee also prevents
> freeing of the protected object.
I need to think more about this, so let's defer it until after the
release, which I am planning for tomorrow (Tuesday) morning, Pacific Time.
If I don't get back to this in a week or so, please do remind me.
Thanx, Paul
> > > > \item[\IX{Unteachable}:]
> > > > A topic, concept, method, or mechanism that the teacher does
> > > > not understand well is therefore uncomfortable teaching.
> > > Many thanks
> > > Zhouyi
> Thanks
> Zhouyi
