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Commit 11a65df5 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

documentation: Remove unnecessary images from requirements 



This commit removes a cutesy cartoon and also a diagram that can
just as easily be represented by text.

Reported-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 514f1eb5

Documentation/RCU/Design/Requirements/2013-08-is-it-dead.png

deleted100644 → 0
−98.5 KiB
Loading image diff...

Documentation/RCU/Design/Requirements/RCUApplicability.svg

deleted100644 → 0
+0 −237
Original line number Diff line number Diff line 
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         style="font-size:427.63009644px;font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;text-align:center;line-height:125%;writing-mode:lr-tb;text-anchor:middle;font-family:Nimbus Sans L;-inkscape-font-specification:Nimbus Sans L"

         id="tspan3017">Read-Mostly, Stale &amp;</tspan></text>

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         style="font-size:427.63009644px;font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;text-align:center;line-height:125%;writing-mode:lr-tb;text-anchor:middle;font-family:Nimbus Sans L;-inkscape-font-specification:Nimbus Sans L"

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       style="font-size:427.63009644px;font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;text-align:center;line-height:125%;writing-mode:lr-tb;text-anchor:middle;fill:#000000;font-family:Nimbus Sans L;-inkscape-font-specification:Nimbus Sans L"><tspan

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         style="font-size:427.63009644px;font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;text-align:center;line-height:125%;writing-mode:lr-tb;text-anchor:middle;font-family:Nimbus Sans L;-inkscape-font-specification:Nimbus Sans L"

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       sodipodi:linespacing="125%">(1) Provide Existence Guarantees For Update-Friendly Mechanisms</text>

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       sodipodi:linespacing="125%">(2) Provide Wait-Free Read-Side Primitives for Real-Time Use)</text>

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       sodipodi:linespacing="125%">(RCU is Very Unlikely to be the Right Tool For The Job, But it Can:</text>

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Documentation/RCU/Design/Requirements/Requirements.html

+20 −8
Original line number Diff line number Diff line
@@ -1120,12 +1120,27 @@ These classes is covered in the following sections. 
<h3><a name="Specialization">Specialization</a></h3>



<p>

RCU is and always has been intended primarily for read-mostly situations, as

illustrated by the following figure.

This means that RCU's read-side primitives are optimized, often at the

RCU is and always has been intended primarily for read-mostly situations,

which means that RCU's read-side primitives are optimized, often at the

expense of its update-side primitives.

Experience thus far is captured by the following list of situations:



<p><img src="RCUApplicability.svg" alt="RCUApplicability.svg" width="70%"></p>

<ol>

<li>	Read-mostly data, where stale and inconsistent data is not

	a problem:   RCU works great!

<li>	Read-mostly data, where data must be consistent:

	RCU works well.

<li>	Read-write data, where data must be consistent:

	RCU <i>might</i> work OK.

	Or not.

<li>	Write-mostly data, where data must be consistent:

	RCU is very unlikely to be the right tool for the job,

	with the following exceptions, where RCU can provide:

	<ol type=a>

	<li>	Existence guarantees for update-friendly mechanisms.

	<li>	Wait-free read-side primitives for real-time use.

	</ol>

</ol>



<p>

This focus on read-mostly situations means that RCU must interoperate
@@ -1171,10 +1186,7 @@ some period of time, so the exact wait period is a judgment call. 
One of our pair of veternarians might wait 30 seconds before pronouncing

the cat dead, while the other might insist on waiting a full minute.

The two veternarians would then disagree on the state of the cat during

the final 30 seconds of the minute following the last heartbeat, as

fancifully illustrated below:



<p><img src="2013-08-is-it-dead.png" alt="2013-08-is-it-dead.png" width="431"></p>

the final 30 seconds of the minute following the last heartbeat.



<p>

Interestingly enough, this same situation applies to hardware.

Documentation/RCU/Design/Requirements/Requirements.htmlx

+20 −8
Original line number Diff line number Diff line
@@ -1257,12 +1257,27 @@ These classes is covered in the following sections. 
<h3><a name="Specialization">Specialization</a></h3>



<p>

RCU is and always has been intended primarily for read-mostly situations, as

illustrated by the following figure.

This means that RCU's read-side primitives are optimized, often at the

RCU is and always has been intended primarily for read-mostly situations,

which means that RCU's read-side primitives are optimized, often at the

expense of its update-side primitives.

Experience thus far is captured by the following list of situations:



<p><img src="RCUApplicability.svg" alt="RCUApplicability.svg" width="70%"></p>

<ol>

<li>	Read-mostly data, where stale and inconsistent data is not

	a problem:   RCU works great!

<li>	Read-mostly data, where data must be consistent:

	RCU works well.

<li>	Read-write data, where data must be consistent:

	RCU <i>might</i> work OK.

	Or not.

<li>	Write-mostly data, where data must be consistent:

	RCU is very unlikely to be the right tool for the job,

	with the following exceptions, where RCU can provide:

	<ol type=a>

	<li>	Existence guarantees for update-friendly mechanisms.

	<li>	Wait-free read-side primitives for real-time use.

	</ol>

</ol>



<p>

This focus on read-mostly situations means that RCU must interoperate
@@ -1330,10 +1345,7 @@ some period of time, so the exact wait period is a judgment call. 
One of our pair of veternarians might wait 30 seconds before pronouncing

the cat dead, while the other might insist on waiting a full minute.

The two veternarians would then disagree on the state of the cat during

the final 30 seconds of the minute following the last heartbeat, as

fancifully illustrated below:



<p><img src="2013-08-is-it-dead.png" alt="2013-08-is-it-dead.png" width="431"></p>

the final 30 seconds of the minute following the last heartbeat.



<p>

Interestingly enough, this same situation applies to hardware.