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>
This commit is contained in:
Paul E. McKenney
Родитель
514f1eb5f4
Коммит
11a65df573
Двоичные данные
Documentation/RCU/Design/Requirements/2013-08-is-it-dead.png
Двоичные данные
Documentation/RCU/Design/Requirements/2013-08-is-it-dead.png
Двоичный файл не отображается.
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До Ширина: | Высота: | Размер: 98 KiB |
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@ -1,237 +0,0 @@
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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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До Ширина: | Высота: | Размер: 10 KiB |
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@ -1120,12 +1120,27 @@ These classes is covered in the following sections.
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<h3><a name="Specialization">Specialization</a></h3>
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<p>
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RCU is and always has been intended primarily for read-mostly situations, as
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illustrated by the following figure.
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This means that RCU's read-side primitives are optimized, often at the
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RCU is and always has been intended primarily for read-mostly situations,
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which means that RCU's read-side primitives are optimized, often at the
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expense of its update-side primitives.
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Experience thus far is captured by the following list of situations:
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<p><img src="RCUApplicability.svg" alt="RCUApplicability.svg" width="70%"></p>
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<ol>
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<li> Read-mostly data, where stale and inconsistent data is not
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a problem: RCU works great!
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<li> Read-mostly data, where data must be consistent:
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RCU works well.
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<li> Read-write data, where data must be consistent:
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RCU <i>might</i> work OK.
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Or not.
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<li> Write-mostly data, where data must be consistent:
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RCU is very unlikely to be the right tool for the job,
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with the following exceptions, where RCU can provide:
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<ol type=a>
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<li> Existence guarantees for update-friendly mechanisms.
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<li> Wait-free read-side primitives for real-time use.
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</ol>
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</ol>
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<p>
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This focus on read-mostly situations means that RCU must interoperate
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@ -1171,10 +1186,7 @@ some period of time, so the exact wait period is a judgment call.
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One of our pair of veternarians might wait 30 seconds before pronouncing
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the cat dead, while the other might insist on waiting a full minute.
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The two veternarians would then disagree on the state of the cat during
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the final 30 seconds of the minute following the last heartbeat, as
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fancifully illustrated below:
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<p><img src="2013-08-is-it-dead.png" alt="2013-08-is-it-dead.png" width="431"></p>
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the final 30 seconds of the minute following the last heartbeat.
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<p>
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Interestingly enough, this same situation applies to hardware.
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@ -1257,12 +1257,27 @@ These classes is covered in the following sections.
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<h3><a name="Specialization">Specialization</a></h3>
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|
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<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>
|
||||
|
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<p>
|
||||
This focus on read-mostly situations means that RCU must interoperate
|
||||
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@ -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.
|
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|||
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