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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-03-15 11:03:36 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-03-31 13:33:21 -0700
commit11a65df5732167519937eabf16a870f5f8bde5ee (patch)
tree3811af398f19e504a9c6f818bfd76ef020b43ad2 /Documentation/RCU
parent514f1eb5f44520d5255b927ad5aabc00db5bc73d (diff)
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>
Diffstat (limited to 'Documentation/RCU')
-rw-r--r--Documentation/RCU/Design/Requirements/2013-08-is-it-dead.pngbin100825 -> 0 bytes
-rw-r--r--Documentation/RCU/Design/Requirements/RCUApplicability.svg237
-rw-r--r--Documentation/RCU/Design/Requirements/Requirements.html28
-rw-r--r--Documentation/RCU/Design/Requirements/Requirements.htmlx28
4 files changed, 40 insertions, 253 deletions
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
index 7496a55e4e7b..000000000000
--- a/Documentation/RCU/Design/Requirements/2013-08-is-it-dead.png
+++ /dev/null
Binary files differ
diff --git a/Documentation/RCU/Design/Requirements/RCUApplicability.svg b/Documentation/RCU/Design/Requirements/RCUApplicability.svg
deleted file mode 100644
index ebcbeee391ed..000000000000
--- 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"
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- <!-- Line: box -->
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- x="1350"
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- <!-- Line: box -->
- <rect
- x="2700"
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- rx="0"
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- 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
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- 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
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- 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 01e12b86e81f..c67a96a2a389 100644
--- 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 3355f1f9384c..d6a84f3e0451 100644
--- 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.