On Thu, Jun 22, 2017 at 07:46:57AM +0900, Akira Yokosawa wrote:
> On 2017/06/21 10:45:41 -0700, Paul E. McKenney wrote:
> > On Wed, Jun 21, 2017 at 07:55:34AM +0900, Akira Yokosawa wrote:
> >> On 2017/06/20 23:28, Akira Yokosawa wrote:
> >>> >From db0fd6b383b551eabecb12dfa21e42093f338b2f Mon Sep 17 00:00:00 2001
> >>> From: Akira Yokosawa <akiyks@xxxxxxxxx>
> >>> Date: Mon, 19 Jun 2017 23:55:31 +0900
> >>> Subject: [PATCH 2/3] toyrcu: Trivial typo fixes (rcu_idx -> rcu_refcnt)
> >>>
> >>> Signed-off-by: Akira Yokosawa <akiyks@xxxxxxxxx>
> >>> ---
> >>> appendix/toyrcu/toyrcu.tex | 12 ++++++------
> >>> 1 file changed, 6 insertions(+), 6 deletions(-)
> >>>
> >>> diff --git a/appendix/toyrcu/toyrcu.tex b/appendix/toyrcu/toyrcu.tex
> >>> index 79fbe33..a7bf6ca 100644
> >>> --- a/appendix/toyrcu/toyrcu.tex
> >>> +++ b/appendix/toyrcu/toyrcu.tex
> >>> @@ -524,10 +524,10 @@ by complementing the value of \co{rcu_idx}, as in \co{rcu_idx = !rcu_idx}.
> >>> Suppose that the old value of \co{rcu_idx} was zero, so that the new
> >>> value is one.
> >>> New readers that arrive after the complement operation will increment
> >>> -\co{rcu_idx[1]}, while the old readers that previously incremented
> >>> -\co{rcu_idx[0]} will decrement \co{rcu_idx[0]} when they exit their
> >>> +\co{rcu_refcnt[1]}, while the old readers that previously incremented
> >>> +\co{rcu_refcnt[0]} will decrement \co{rcu_refcnt[0]} when they exit their
> >>> RCU read-side critical sections.
> >>> -This means that the value of \co{rcu_idx[0]} will no longer be incremented,
> >>> +This means that the value of \co{rcu_refcnt[0]} will no longer be incremented,
> >>> and thus will be monotonically decreasing.\footnote{
> >>> There is a race condition that this ``monotonically decreasing''
> >>> statement ignores.
> >>> @@ -616,11 +616,11 @@ Lines~6 and 19 acquire and release \co{rcu_gp_lock} in order to
> >>> prevent more than one concurrent instance of \co{synchronize_rcu()}.
> >>> Lines~7-8 pick up the value of \co{rcu_idx} and complement it,
> >>> respectively, so that subsequent instances of \co{rcu_read_lock()}
> >>> -will use a different element of \co{rcu_idx} that did preceding
> >>> +will use a different element of \co{rcu_refcnt} that did preceding
> >>> instances.
> >>
> >> I have a little trouble with this sentence. Do you mean:
> >>
> >> ..., so that subsequent instances of \co{rcu_read_lock()}
> >> will use a different element of \co{rcu_refcnt} from the one did preceding
> >> instances.
> >
> > Just to fully illustrate:
> >
> > 1. Suppose that rcu_idx is initially zero.
> >
> > 2. Any rcu_read_lock() invocations running at this point will
> > therefore be incrementing rcu_refcnt[0].
> >
> > 3. A synchronize_srcu() instance now complements rcu_idx, so that
> > its new value is one.
> >
> > 4. Any rcu_read_lock() invocations from step 2 that fetched rcu_idx
> > before step 3 completed will still increment rcu_refcnt[0].
> >
> > 5. However, any subsequent rcu_read_lock() invocations will instead
> > increment rcu_refcnt[1]. (At least until the next invocation
> > of synchronize_rcu().)
> >
> > Does that help, or am I missing the point of your question?
>
> Thanks. This is what I guessed you mean.
>
> So what bothered me was the structure of the clause. I rarely see a sentence like:
>
> I will buy a different model of PC that did you.
>
> I can't figure out the grammatical role of "that" here.
Color me blind!!! The "that" should be "than". My brain autocorrected on
first reading, so I couldn't even see it. I queued the following patch.
Thanx, Paul
------------------------------------------------------------------------
commit ed403934aeff63a46db4412d6a485f42d39daabd
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Date: Wed Jun 21 16:03:43 2017 -0700
toyrcu: Typo s/that/than/
Reported-by: Akira Yokosawa <akiyks@xxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
diff --git a/appendix/toyrcu/toyrcu.tex b/appendix/toyrcu/toyrcu.tex
index a7bf6ca25616..3f19662aa1c2 100644
--- a/appendix/toyrcu/toyrcu.tex
+++ b/appendix/toyrcu/toyrcu.tex
@@ -616,7 +616,7 @@ Lines~6 and 19 acquire and release \co{rcu_gp_lock} in order to
prevent more than one concurrent instance of \co{synchronize_rcu()}.
Lines~7-8 pick up the value of \co{rcu_idx} and complement it,
respectively, so that subsequent instances of \co{rcu_read_lock()}
-will use a different element of \co{rcu_refcnt} that did preceding
+will use a different element of \co{rcu_refcnt} than did preceding
instances.
Lines~10-12 then wait for the prior element of \co{rcu_refcnt} to
reach zero, with the memory barrier on line~9 ensuring that the check
--
To unsubscribe from this list: send the line "unsubscribe perfbook" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
