On Mon, 20 Dec 2021 09:43:04 -0800, Paul E. McKenney 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.
> \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.
> \item[\IX{Unteachable}:]
> A topic, concept, method, or mechanism that the teacher does
> not understand well is therefore uncomfortable teaching.
>
Looks good to me!
Thanks, Akira
