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: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/Documentation/RCU/Design/Requirements/2013-08-is-it-dead.png b/Documentation/RCU/Design/Requirements/2013-08-is-it-dead.png
deleted file mode 100644 (file)
index 7496a55..0000000
Binary files a/Documentation/RCU/Design/Requirements/2013-08-is-it-dead.png and /dev/null differ

diff --git a/Documentation/RCU/Design/Requirements/RCUApplicability.svg b/Documentation/RCU/Design/Requirements/RCUApplicability.svg
deleted file mode 100644 (file)
index ebcbeee..0000000
--- a/Documentation/RCU/Design/Requirements/RCUApplicability.svg
+++ /dev/null
@@ -1,237 +0,0 @@
-<?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<!-- Creator: fig2dev Version 3.2 Patchlevel 5d -->
-
-<!-- CreationDate: Tue Mar  4 18:34:25 2014 -->
-
-<!-- Magnification: 3.000 -->
-
-<svg
-   xmlns:dc="http://purl.org/dc/elements/1.1/"
-   xmlns:cc="http://creativecommons.org/ns#"
-   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
-   xmlns:svg="http://www.w3.org/2000/svg"
-   xmlns="http://www.w3.org/2000/svg"
-   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
-   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
-   width="1089.1382"
-   height="668.21368"
-   viewBox="-2121 -36 14554.634 8876.4061"
-   id="svg2"
-   version="1.1"
-   inkscape:version="0.48.3.1 r9886"
-   sodipodi:docname="RCUApplicability.svg">
-  <metadata
-     id="metadata40">
-    <rdf:RDF>
-      <cc:Work
-         rdf:about="">
-        <dc:format>image/svg+xml</dc:format>
-        <dc:type
-           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
-        <dc:title />
-      </cc:Work>
-    </rdf:RDF>
-  </metadata>
-  <defs
-     id="defs38" />
-  <sodipodi:namedview
-     pagecolor="#ffffff"
-     bordercolor="#666666"
-     borderopacity="1"
-     objecttolerance="10"
-     gridtolerance="10"
-     guidetolerance="10"
-     inkscape:pageopacity="0"
-     inkscape:pageshadow="2"
-     inkscape:window-width="849"
-     inkscape:window-height="639"
-     id="namedview36"
-     showgrid="false"
-     inkscape:zoom="0.51326165"
-     inkscape:cx="544.56912"
-     inkscape:cy="334.10686"
-     inkscape:window-x="149"
-     inkscape:window-y="448"
-     inkscape:window-maximized="0"
-     inkscape:current-layer="g4"
-     fit-margin-top="5"
-     fit-margin-left="5"
-     fit-margin-right="5"
-     fit-margin-bottom="5" />
-  <g
-     style="fill:none;stroke-width:0.025in"
-     id="g4"
-     transform="translate(-2043.6828,14.791398)">
-    <!-- Line: box -->
-    <rect
-       x="0"
-       y="0"
-       width="14400"
-       height="8775"
-       rx="0"
-       style="fill:#ffa1a1;stroke:#000000;stroke-width:21;stroke-linecap:butt;stroke-linejoin:miter"
-       id="rect6" />
-    <!-- Line: box -->
-    <rect
-       x="1350"
-       y="0"
-       width="11700"
-       height="6075"
-       rx="0"
-       style="fill:#ffff00;stroke:#000000;stroke-width:21;stroke-linecap:butt;stroke-linejoin:miter"
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-    <!-- Line: box -->
-    <rect
-       x="2700"
-       y="0"
-       width="9000"
-       height="4275"
-       rx="0"
-       style="fill:#00ff00;stroke:#000000;stroke-width:21;stroke-linecap:butt;stroke-linejoin:miter"
-       id="rect10" />
-    <!-- Line: box -->
-    <rect
-       x="4050"
-       y="0"
-       width="6300"
-       height="2475"
-       rx="0"
-       style="fill:#87cfff;stroke:#000000;stroke-width:21;stroke-linecap:butt;stroke-linejoin:miter"
-       id="rect12" />
-    <!-- Text -->
-    <text
-       xml:space="preserve"
-       x="7200"
-       y="900"
-       font-style="normal"
-       font-weight="normal"
-       font-size="324"
-       id="text14"
-       sodipodi:linespacing="125%"
-       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
-         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>
-    <!-- Text -->
-    <text
-       xml:space="preserve"
-       x="7200"
-       y="1350"
-       font-style="normal"
-       font-weight="normal"
-       font-size="324"
-       id="text16"
-       sodipodi:linespacing="125%"
-       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
-         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="tspan3019">Inconsistent Data OK</tspan></text>
-    <!-- Text -->
-    <text
-       xml:space="preserve"
-       x="7200"
-       y="1800"
-       font-style="normal"
-       font-weight="normal"
-       font-size="324"
-       id="text18"
-       sodipodi:linespacing="125%"
-       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
-         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="tspan3021">(RCU Works Great!!!)</tspan></text>
-    <!-- Text -->
-    <text
-       xml:space="preserve"
-       x="7200"
-       y="3825"
-       font-style="normal"
-       font-weight="normal"
-       font-size="324"
-       id="text20"
-       sodipodi:linespacing="125%"
-       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
-         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="tspan3023">(RCU Works Well)</tspan></text>
-    <!-- Text -->
-    <text
-       xml:space="preserve"
-       x="7200"
-       y="3375"
-       font-style="normal"
-       font-weight="normal"
-       font-size="324"
-       id="text22"
-       sodipodi:linespacing="125%"
-       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
-         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="tspan3025">Read-Mostly, Need Consistent Data</tspan></text>
-    <!-- Text -->
-    <text
-       xml:space="preserve"
-       x="7200"
-       y="5175"
-       font-style="normal"
-       font-weight="normal"
-       font-size="324"
-       id="text24"
-       sodipodi:linespacing="125%"
-       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
-         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="tspan3027">Read-Write, Need Consistent Data</tspan></text>
-    <!-- Text -->
-    <text
-       xml:space="preserve"
-       x="7200"
-       y="6975"
-       font-style="normal"
-       font-weight="normal"
-       font-size="324"
-       id="text26"
-       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"
-       sodipodi:linespacing="125%">Update-Mostly, Need Consistent Data</text>
-    <!-- Text -->
-    <text
-       xml:space="preserve"
-       x="7200"
-       y="5625"
-       font-style="normal"
-       font-weight="normal"
-       font-size="324"
-       id="text28"
-       sodipodi:linespacing="125%"
-       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
-         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="tspan3029">(RCU Might Be OK...)</tspan></text>
-    <!-- Text -->
-    <text
-       xml:space="preserve"
-       x="7200"
-       y="7875"
-       font-style="normal"
-       font-weight="normal"
-       font-size="324"
-       id="text30"
-       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"
-       sodipodi:linespacing="125%">(1) Provide Existence Guarantees For Update-Friendly Mechanisms</text>
-    <!-- Text -->
-    <text
-       xml:space="preserve"
-       x="7200"
-       y="8325"
-       font-style="normal"
-       font-weight="normal"
-       font-size="324"
-       id="text32"
-       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"
-       sodipodi:linespacing="125%">(2) Provide Wait-Free Read-Side Primitives for Real-Time Use)</text>
-    <!-- Text -->
-    <text
-       xml:space="preserve"
-       x="7200"
-       y="7425"
-       font-style="normal"
-       font-weight="normal"
-       font-size="324"
-       id="text34"
-       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"
-       sodipodi:linespacing="125%">(RCU is Very Unlikely to be the Right Tool For The Job, But it Can:</text>
-  </g>
-</svg>

diff --git a/Documentation/RCU/Design/Requirements/Requirements.html b/Documentation/RCU/Design/Requirements/Requirements.html
index 01e12b8..c67a96a 100644 (file)
--- a/Documentation/RCU/Design/Requirements/Requirements.html
+++ b/Documentation/RCU/Design/Requirements/Requirements.html
@@ -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.

diff --git a/Documentation/RCU/Design/Requirements/Requirements.htmlx b/Documentation/RCU/Design/Requirements/Requirements.htmlx
index 3355f1f..d6a84f3 100644 (file)
--- a/Documentation/RCU/Design/Requirements/Requirements.htmlx
+++ b/Documentation/RCU/Design/Requirements/Requirements.htmlx
@@ -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.