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'
> \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"?)
> \item[\IX{Unteachable}:]
> A topic, concept, method, or mechanism that the teacher does
> not understand well is therefore uncomfortable teaching.
Many thanks
Zhouyi
