lkml.org 
[lkml]   [2015]   [Dec]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH tip/core/rcu 1/8] documentation: Record RCU requirements
On Fri, Dec 04, 2015 at 05:56:01PM -0800, Paul E. McKenney wrote:
> On Fri, Dec 04, 2015 at 04:38:42PM -0800, Josh Triplett wrote:

[ . . . ]

> > Because you don't want to complicate the script, or because you don't
> > want to accidentally edit the wrong version? (Note that a carefully
> > written script would mean it doesn't matter which version you edit.)
>
> I prefer the simpler script.
>
> > A third alternative would be to include the answers inline right after
> > the questions, and optionally add a tiny bit of JavaScript that hides
> > them by default and lets you click to show the answer. :)
>
> That does have some advantages. I would welcome a patch that added
> the JavaScript.

And I did try a CSS approach with this CSS definition:

<style media="screen" type="text/css">
.quick-quiz-wrap {
position: relative;
}
.quick-quiz-wrap .quick-quiz-content {
display: none;
position: absolute;
bottom: -10px;
left: 10px;
right: 10px;
background-color: lightgrey;
padding: 20px;
}
.quick-quiz-wrap:hover .quick-quiz-content {
display: block;
}
</style>

I linked to this as follows:

<link rel="stylesheet" type="text/css" href="../quick-quiz.css" media="screen">

And used it like this:

<p><b>Quick Quiz:</b>
Wait a minute!
You said that updaters can make useful forward progress concurrently
with readers, but pre-existing readers will block
<tt>synchronize_rcu()</tt>!!!
Just who are you trying to fool???
</p>

<div class="quick-quiz-wrap">
<b>Quick Quiz Answer</b>
<div class="quick-quiz-content">
<p>First, if updaters do not wish to be blocked
by readers, they can use <tt>call_rcu()</tt> or
<tt>kfree_rcu()</tt>, which will be discussed later.
Second, even when using <tt>synchronize_rcu()</tt>,
the other update-side code does run concurrently with
readers, whether pre-existing or not.
</div>
</div>

This proved fragile. It worked in trivial cases, but with non-trivial
content in a non-trivial document, it refused to show anything on mouse
hover. Even in trivial cases, it sometimes made strange choices on
where to display the text. At this point, I drop back to the old-school
scripted approach. It has the advantage of working consistently and
providing good user experience, with the HTML unconditionally present. ;-)

Thanx, Paul



\
 
 \ /
  Last update: 2015-12-05 22:21    [W:0.070 / U:0.104 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site