Re: Feedback on Chapter 9

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Sat, Jul 23, 2016 at 08:06:16PM +0900, Akira Yokosawa wrote:
> On 2016/07/21 23:56:25 +0900, Akira Yokosawa wrote:
> > Hi Paul,
> > 
> > I have a few comments on Chapter 9.

Thank you for the review and comments!

> > 1st one is on the description of Figure 9.5.
> > When one reads the following,
> > 
> >> The ``ideal'' trace was generated by running the sequential code
> >> shown in Figure 9.2.
> > 
> > one might wonder, "Wait, why a sequential code scales with the number
> > of CPUs (threads)?"
> > 
> > Of course, route_lookup() of Figure 9.2 can be run concurrently on
> > multiple CPUs. But it might not be obvious for a novice reader.
> > Maybe you can make this as a Quick Quiz.

I like that idea, but I already have a pair of Quick Quizzes there, so
I added the following:

	which works only because this is a read-only workload.

With a bit more context:

	The "ideal" trace was generated by running the sequential
	code shown in Figure 9.2, which works only because this is a
	read-only workload.

> > 2nd one is for Figure 9.33.
> > 
> > Here, RCU QSBR (quiescent-state-based-reclamation) is mentioned.
> > However, there seems to be no explanation of what actually it is.
> > Do you plan to add some explanation or reference?
> 
> It seems like it is (essentially) the same as "RCU Based on Quiescent
> States" described in Section 9.5.5.9, isn't it? 

Good point, but Figure 9.19 is an earlier example.  I added the
definition in the discussion of this figure, and then a backwards
reference from the discussion of Figure 9.33 to both Figure 9.19
and the section it appears in.

> If it is, it might be enough to just add a reference to the section
> and use a consistent abbreviation.
> 
> Also, Quick Quiz 9.72 is essentially the same as Quick Quiz 9.26, isn't it?
> It seems like we need some more tweaks to improve overall consistency.

I am happy having them both, given that this is often a point of
confusion.  What tweaks would you like to see?  (I should probably
remove the "WTF?", if that is your concern.)

> And here are some additional feedback regarding Chapter 9:
> 
> * In Answer of Quick Quiz 9.28, SRCU and "RCU Classic" appear for the first
>   time (if you are reading Chapter 9 from the beginning) without any
>   explanation of what they are.

I changed the SRCU primitives into RCU primitives, and then changed
"RCU Classic" into "RCU QSBR".

> * Just after Quick Quiz 9.30, discussion on LKML is mentioned. "git blame"
>   shows that this sentence was there in the initial commit in 2008.
>   we need a reference here. Also, Section 9.2 is mentioned as a summary
>   of the discussion, but Section 13.2 seems like where the summary exists
>   now.

Good catch!  I removed the "LKML" and updated the reference to
Section 13.2, as you suggested.

							Thanx, Paul