[PATCH tip/core/rcu 05/20] doc: rcu: Remove rcu_dynticks from Data-Structures

From: Paul E. McKenney
Date: Sun Nov 11 2018 - 14:58:09 EST

Next message: Paul E. McKenney: "[PATCH tip/core/rcu 10/20] doc: rcu: Update core and full API in whatisRCU"
Previous message: Chris Packham: "Re: [PATCH v6 5/9] dt-bindings: ARM: document marvell,ecc-enable binding"
In reply to: Paul E. McKenney: "[PATCH tip/core/rcu 19/20] doc: Correct parameter in stallwarn"
Next in thread: Paul E. McKenney: "[PATCH tip/core/rcu 10/20] doc: rcu: Update core and full API in whatisRCU"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

From: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx>

rcu_dynticks was folded into rcu_data structure. Update the data
structures RCU document accordingly.

Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Cc: <kernel-team@xxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxx>
---
.../BigTreeClassicRCUBHdyntick.svg | 695 ------------------
.../Data-Structures/Data-Structures.html | 90 +--
2 files changed, 25 insertions(+), 760 deletions(-)
delete mode 100644 Documentation/RCU/Design/Data-Structures/BigTreeClassicRCUBHdyntick.svg

diff --git a/Documentation/RCU/Design/Data-Structures/BigTreeClassicRCUBHdyntick.svg b/Documentation/RCU/Design/Data-Structures/BigTreeClassicRCUBHdyntick.svg
deleted file mode 100644
index 21ba7823479d..000000000000
--- a/Documentation/RCU/Design/Data-Structures/BigTreeClassicRCUBHdyntick.svg
+++ /dev/null
@@ -1,695 +0,0 @@
-<?xml version="1.0" encoding="UTF-8" standalone="no"?>
-
-
-
-
-
-
-<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="5.7in"
- height="8.6in"
- viewBox="-44 -44 6838 10288"
- id="svg2"
- version="1.1"
- inkscape:version="0.48.4 r9939"
- sodipodi:docname="BigTreeClassicRCUBHdyntick.fig">
- <metadata
- id="metadata166">
- <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></dc:title>
- </cc:Work>
- </rdf:RDF>
- </metadata>
- <defs
- id="defs164">
- <marker
- inkscape:stockid="Arrow1Mend"
- orient="auto"
- refY="0.0"
- refX="0.0"
- id="Arrow1Mend"
- style="overflow:visible;">
- <path
- id="path3924"
- d="M 0.0,0.0 L 5.0,-5.0 L -12.5,0.0 L 5.0,5.0 L 0.0,0.0 z "
- style="fill-rule:evenodd;stroke:#000000;stroke-width:1.0pt;"
- transform="scale(0.4) rotate(180) translate(10,0)" />
- </marker>
- <marker
- inkscape:stockid="Arrow2Lend"
- orient="auto"
- refY="0.0"
- refX="0.0"
- id="Arrow2Lend"
- style="overflow:visible;">
- <path
- id="path3936"
- style="fill-rule:evenodd;stroke-width:0.62500000;stroke-linejoin:round;"
- d="M 8.7185878,4.0337352 L -2.2072895,0.016013256 L 8.7185884,-4.0017078 C 6.9730900,-1.6296469 6.9831476,1.6157441 8.7185878,4.0337352 z "
- transform="scale(1.1) rotate(180) translate(1,0)" />
- </marker>
- </defs>
- <sodipodi:namedview
- pagecolor="#ffffff"
- bordercolor="#666666"
- borderopacity="1"
- objecttolerance="10"
- gridtolerance="10"
- guidetolerance="10"
- inkscape:pageopacity="0"
- inkscape:pageshadow="2"
- inkscape:window-width="845"
- inkscape:window-height="988"
- id="namedview162"
- showgrid="false"
- inkscape:zoom="1.0452196"
- inkscape:cx="256.5"
- inkscape:cy="387.00003"
- inkscape:window-x="356"
- inkscape:window-y="61"
- inkscape:window-maximized="0"
- inkscape:current-layer="g4" />
- <g
- style="stroke-width:.025in; fill:none"
- id="g4">
- 
- <rect
- x="450"
- y="0"
- width="6300"
- height="7350"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#ffffff; "
- id="rect6" />
- 
- <rect
- x="4950"
- y="4950"
- width="1500"
- height="900"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#87cfff; "
- id="rect8" />
- 
- <rect
- x="750"
- y="600"
- width="5700"
- height="3750"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#ffff00; "
- id="rect10" />
- 
- <polyline
- points="5250,8100 5688,5912 "
- style="stroke:#00ff00;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; "
- id="polyline12" />
- 
- <polyline
- points="5714 6068 5704 5822 5598 6044 "
- style="stroke:#00ff00;stroke-width:14;stroke-miterlimit:8; "
- id="polyline14" />
- 
- <polyline
- points="4050,9300 4486,7262 "
- style="stroke:#00ff00;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; "
- id="polyline16" />
- 
- <polyline
- points="4514 7418 4506 7172 4396 7394 "
- style="stroke:#00ff00;stroke-width:14;stroke-miterlimit:8; "
- id="polyline18" />
- 
- <polyline
- points="1040,9300 1476,7262 "
- style="stroke:#00ff00;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; "
- id="polyline20" />
- 
- <polyline
- points="1504 7418 1496 7172 1386 7394 "
- style="stroke:#00ff00;stroke-width:14;stroke-miterlimit:8; "
- id="polyline22" />
- 
- <polyline
- points="2240,8100 2676,6062 "
- style="stroke:#00ff00;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; "
- id="polyline24" />
- 
- <polyline
- points="2704 6218 2696 5972 2586 6194 "
- style="stroke:#00ff00;stroke-width:14;stroke-miterlimit:8; "
- id="polyline26" />
- 
- <rect
- x="0"
- y="450"
- width="6300"
- height="7350"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#ffffff; "
- id="rect28" />
- 
- <rect
- x="300"
- y="1050"
- width="5700"
- height="3750"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#ffff00; "
- id="rect30" />
- 
- <polyline
- points="1350,3450 2350,2590 "
- style="stroke:#00d1d1;stroke-width:30.0045575;stroke-linejoin:miter;stroke-linecap:butt;stroke-miterlimit:4;stroke-dasharray:none;marker-end:url(#Arrow1Mend)"
- id="polyline32" />
- 
- 
- <polyline
- points="4950,3450 3948,2590 "
- style="stroke:#00d1d1;stroke-width:30.0045575;stroke-linejoin:miter;stroke-linecap:butt;stroke-miterlimit:4;stroke-dasharray:none;marker-end:url(#Arrow1Mend)"
- id="polyline36" />
- 
- 
- <polyline
- points="4050,6600 4050,4414 "
- style="stroke:#00d1d1;stroke-width:30.00455750000000066;stroke-linejoin:miter;stroke-linecap:butt;stroke-miterlimit:4;stroke-dasharray:none;marker-end:url(#Arrow1Mend)"
- id="polyline40" />
- 
- 
- <polyline
- points="1050,6600 1050,4414 "
- style="stroke:#00d1d1;stroke-width:30.00455750000000066;stroke-linejoin:miter;stroke-linecap:butt;stroke-miterlimit:4;stroke-dasharray:none;marker-end:url(#Arrow1Mend)"
- id="polyline44" />
- 
- 
- <polyline
- points="2250,5400 2250,4414 "
- style="stroke:#00d1d1;stroke-width:30.00455750000000066;stroke-linejoin:miter;stroke-linecap:butt;stroke-miterlimit:4;stroke-dasharray:none;marker-end:url(#Arrow1Mend)"
- id="polyline48" />
- 
- 
- <polyline
- points="2250,8100 2250,6364 "
- style="stroke:#00ff00;stroke-width:30;stroke-linejoin:miter;stroke-linecap:butt;marker-end:url(#Arrow1Mend)"
- id="polyline52" />
- 
- 
- <polyline
- points="1050,9300 1050,7564 "
- style="stroke:#00ff00;stroke-width:30;stroke-linejoin:miter;stroke-linecap:butt;marker-end:url(#Arrow1Mend)"
- id="polyline56" />
- 
- 
- <polyline
- points="4050,9300 4050,7564 "
- style="stroke:#00ff00;stroke-width:30;stroke-linejoin:miter;stroke-linecap:butt;marker-end:url(#Arrow1Mend)"
- id="polyline60" />
- 
- 
- <polyline
- points="5250,8100 5250,6364 "
- style="stroke:#00ff00;stroke-width:30;stroke-linejoin:miter;stroke-linecap:butt;marker-end:url(#Arrow1Mend)"
- id="polyline64" />
- 
- 
- <circle
- cx="2850"
- cy="3900"
- r="76"
- style="fill:#000000;stroke:#000000;stroke-width:14;"
- id="circle68" />
- 
- <circle
- cx="3150"
- cy="3900"
- r="76"
- style="fill:#000000;stroke:#000000;stroke-width:14;"
- id="circle70" />
- 
- <circle
- cx="3450"
- cy="3900"
- r="76"
- style="fill:#000000;stroke:#000000;stroke-width:14;"
- id="circle72" />
- 
- <circle
- cx="1350"
- cy="5100"
- r="76"
- style="fill:#000000;stroke:#000000;stroke-width:14;"
- id="circle74" />
- 
- <circle
- cx="1650"
- cy="5100"
- r="76"
- style="fill:#000000;stroke:#000000;stroke-width:14;"
- id="circle76" />
- 
- <circle
- cx="1950"
- cy="5100"
- r="76"
- style="fill:#000000;stroke:#000000;stroke-width:14;"
- id="circle78" />
- 
- <circle
- cx="4350"
- cy="5100"
- r="76"
- style="fill:#000000;stroke:#000000;stroke-width:14;"
- id="circle80" />
- 
- <circle
- cx="4650"
- cy="5100"
- r="76"
- style="fill:#000000;stroke:#000000;stroke-width:14;"
- id="circle82" />
- 
- <circle
- cx="4950"
- cy="5100"
- r="76"
- style="fill:#000000;stroke:#000000;stroke-width:14;"
- id="circle84" />
- 
- <rect
- x="750"
- y="3450"
- width="1800"
- height="900"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#ffbfbf; "
- id="rect86" />
- 
- <rect
- x="300"
- y="6600"
- width="1500"
- height="900"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#87cfff; "
- id="rect88" />
- 
- <rect
- x="3750"
- y="3450"
- width="1800"
- height="900"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#ffbfbf; "
- id="rect90" />
- 
- <rect
- x="4500"
- y="5400"
- width="1500"
- height="900"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#87cfff; "
- id="rect92" />
- 
- <rect
- x="3300"
- y="6600"
- width="1500"
- height="900"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#87cfff; "
- id="rect94" />
- 
- <rect
- x="2250"
- y="1650"
- width="1800"
- height="900"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#ffbfbf; "
- id="rect96" />
- 
- <rect
- x="0"
- y="9300"
- width="2100"
- height="900"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#00ff00; "
- id="rect98" />
- 
- <rect
- x="1350"
- y="8100"
- width="2100"
- height="900"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#00ff00; "
- id="rect100" />
- 
- <rect
- x="3000"
- y="9300"
- width="2100"
- height="900"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#00ff00; "
- id="rect102" />
- 
- <rect
- x="4350"
- y="8100"
- width="2100"
- height="900"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#00ff00; "
- id="rect104" />
- 
- <rect
- x="1500"
- y="5400"
- width="1500"
- height="900"
- rx="0"
- style="stroke:#000000;stroke-width:30; stroke-linejoin:miter; stroke-linecap:butt; fill:#87cfff; "
- id="rect106" />
- 
- <text
- xml:space="preserve"
- x="6450"
- y="300"
- fill="#000000"
- font-family="Helvetica"
- font-style="normal"
- font-weight="normal"
- font-size="192"
- text-anchor="end"
- id="text108">rcu_bh</text>
- 
- <text
- xml:space="preserve"
- x="3150"
- y="1950"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text110">struct</text>
- 
- <text
- xml:space="preserve"
- x="3150"
- y="2250"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text112">rcu_node</text>
- 
- <text
- xml:space="preserve"
- x="1650"
- y="3750"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text114">struct</text>
- 
- <text
- xml:space="preserve"
- x="1650"
- y="4050"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text116">rcu_node</text>
- 
- <text
- xml:space="preserve"
- x="4650"
- y="4050"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text118">rcu_node</text>
- 
- <text
- xml:space="preserve"
- x="4650"
- y="3750"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text120">struct</text>
- 
- <text
- xml:space="preserve"
- x="2250"
- y="5700"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text122">struct</text>
- 
- <text
- xml:space="preserve"
- x="2250"
- y="6000"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text124">rcu_data</text>
- 
- <text
- xml:space="preserve"
- x="1050"
- y="6900"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text126">struct</text>
- 
- <text
- xml:space="preserve"
- x="1050"
- y="7200"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text128">rcu_data</text>
- 
- <text
- xml:space="preserve"
- x="5250"
- y="5700"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text130">struct</text>
- 
- <text
- xml:space="preserve"
- x="5250"
- y="6000"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text132">rcu_data</text>
- 
- <text
- xml:space="preserve"
- x="4050"
- y="6900"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text134">struct</text>
- 
- <text
- xml:space="preserve"
- x="4050"
- y="7200"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text136">rcu_data</text>
- 
- <text
- xml:space="preserve"
- x="450"
- y="1350"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="start"
- id="text138">struct rcu_state</text>
- 
- <text
- xml:space="preserve"
- x="1050"
- y="9600"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text140">struct</text>
- 
- <text
- xml:space="preserve"
- x="1050"
- y="9900"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text142">rcu_dynticks</text>
- 
- <text
- xml:space="preserve"
- x="4050"
- y="9600"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text144">struct</text>
- 
- <text
- xml:space="preserve"
- x="4050"
- y="9900"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text146">rcu_dynticks</text>
- 
- <text
- xml:space="preserve"
- x="2400"
- y="8400"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text148">struct</text>
- 
- <text
- xml:space="preserve"
- x="2400"
- y="8700"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text150">rcu_dynticks</text>
- 
- <text
- xml:space="preserve"
- x="5400"
- y="8400"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text152">struct</text>
- 
- <text
- xml:space="preserve"
- x="5400"
- y="8700"
- fill="#000000"
- font-family="Courier"
- font-style="normal"
- font-weight="bold"
- font-size="192"
- text-anchor="middle"
- id="text154">rcu_dynticks</text>
- 
- <text
- xml:space="preserve"
- x="6000"
- y="750"
- fill="#000000"
- font-family="Helvetica"
- font-style="normal"
- font-weight="normal"
- font-size="192"
- text-anchor="end"
- id="text156">rcu_sched</text>
- 
- <polyline
- points="5250,5400 5250,4414 "
- style="stroke:#00d1d1;stroke-width:30.00455750000000066;stroke-linejoin:miter;stroke-linecap:butt;stroke-miterlimit:4;stroke-dasharray:none;marker-end:url(#Arrow1Mend)"
- id="polyline158" />
- 
- </g>
-</svg>
diff --git a/Documentation/RCU/Design/Data-Structures/Data-Structures.html b/Documentation/RCU/Design/Data-Structures/Data-Structures.html
index 476b1ac38e4c..4eb603e3a005 100644
--- a/Documentation/RCU/Design/Data-Structures/Data-Structures.html
+++ b/Documentation/RCU/Design/Data-Structures/Data-Structures.html
@@ -23,8 +23,6 @@ to each other.
The <tt>rcu_segcblist</tt> Structure</a>
<li> <a href="#The rcu_data Structure">
The <tt>rcu_data</tt> Structure</a>
-<li> <a href="#The rcu_dynticks Structure">
- The <tt>rcu_dynticks</tt> Structure</a>
<li> <a href="#The rcu_head Structure">
The <tt>rcu_head</tt> Structure</a>
<li> <a href="#RCU-Specific Fields in the task_struct Structure">
@@ -174,16 +172,8 @@ said to be in <i>dyntick-idle mode</i>.
RCU must handle dyntick-idle CPUs specially
because RCU would otherwise wake up each CPU on every grace period,
which would defeat the whole purpose of <tt>CONFIG_NO_HZ_IDLE</tt>.
-RCU uses the <tt>rcu_dynticks</tt> structure to track
-which CPUs are in dyntick idle mode, as shown below:
-
-</p><p><img src="BigTreeClassicRCUBHdyntick.svg" alt="BigTreeClassicRCUBHdyntick.svg" width="33%">
-
-</p><p>However, if a CPU is in dyntick-idle mode, it is in that mode
-for all flavors of RCU.
-Therefore, a single <tt>rcu_dynticks</tt> structure is allocated per
-CPU, and all of a given CPU's <tt>rcu_data</tt> structures share
-that <tt>rcu_dynticks</tt>, as shown in the figure.
+RCU uses the dynticks related fields in the <tt>rcu_data</tt> structure
+to track which CPUs are in dyntick idle mode.

</p><p>Kernels built with <tt>CONFIG_PREEMPT_RCU</tt> support
rcu_preempt in addition to rcu_sched and rcu_bh, as shown below:
@@ -216,9 +206,6 @@ its own synchronization:
<li> Each <tt>rcu_node</tt> structure has a spinlock.
<li> The fields in <tt>rcu_data</tt> are private to the corresponding
CPU, although a few can be read and written by other CPUs.
-<li> Similarly, the fields in <tt>rcu_dynticks</tt> are private
- to the corresponding CPU, although a few can be read by
- other CPUs.
</ol>

<p>It is important to note that different data structures can have
@@ -274,11 +261,6 @@ follows:
access to this information from the corresponding CPU.
Finally, this structure records past dyntick-idle state
for the corresponding CPU and also tracks statistics.
-<li> <tt>rcu_dynticks</tt>:
- This per-CPU structure tracks the current dyntick-idle
- state for the corresponding CPU.
- Unlike the other three structures, the <tt>rcu_dynticks</tt>
- structure is not replicated per RCU flavor.
<li> <tt>rcu_head</tt>:
This structure represents RCU callbacks, and is the
only structure allocated and managed by RCU users.
@@ -289,8 +271,8 @@ follows:
<p>If all you wanted from this article was a general notion of how
RCU's data structures are related, you are done.
Otherwise, each of the following sections give more details on
-the <tt>rcu_state</tt>, <tt>rcu_node</tt>, <tt>rcu_data</tt>,
-and <tt>rcu_dynticks</tt> data structures.
+the <tt>rcu_state</tt>, <tt>rcu_node</tt> and <tt>rcu_data</tt> data
+structures.

<h3><a name="The rcu_state Structure">
The <tt>rcu_state</tt> Structure</a></h3>
@@ -1017,30 +999,19 @@ as follows:

<pre>
1 int cpu;
- 2 struct rcu_state *rsp;
- 3 struct rcu_node *mynode;
- 4 struct rcu_dynticks *dynticks;
- 5 unsigned long grpmask;
- 6 bool beenonline;
+ 2 struct rcu_node *mynode;
+ 3 unsigned long grpmask;
+ 4 bool beenonline;
</pre>

<p>The <tt>->cpu</tt> field contains the number of the
-corresponding CPU, the <tt>->rsp</tt> pointer references
-the corresponding <tt>rcu_state</tt> structure (and is most frequently
-used to locate the name of the corresponding flavor of RCU for tracing),
-and the <tt>->mynode</tt> field references the corresponding
-<tt>rcu_node</tt> structure.
+corresponding CPU and the <tt>->mynode</tt> field references the
+corresponding <tt>rcu_node</tt> structure.
The <tt>->mynode</tt> is used to propagate quiescent states
up the combining tree.
-<p>The <tt>->dynticks</tt> pointer references the
-<tt>rcu_dynticks</tt> structure corresponding to this
-CPU.
-Recall that a single per-CPU instance of the <tt>rcu_dynticks</tt>
-structure is shared among all flavors of RCU.
-These first four fields are constant and therefore require not
-synchronization.
+These two fields are constant and therefore do not require synchronization.

-</p><p>The <tt>->grpmask</tt> field indicates the bit in
+<p>The <tt>->grpmask</tt> field indicates the bit in
the <tt>->mynode->qsmask</tt> corresponding to this
<tt>rcu_data</tt> structure, and is also used when propagating
quiescent states.
@@ -1181,26 +1152,22 @@ Finally, the <tt>->dynticks_fqs</tt> field is used to
count the number of times this CPU is determined to be in
dyntick-idle state, and is used for tracing and debugging purposes.

-<h3><a name="The rcu_dynticks Structure">
-The <tt>rcu_dynticks</tt> Structure</a></h3>
-
-<p>The <tt>rcu_dynticks</tt> maintains the per-CPU dyntick-idle state
-for the corresponding CPU.
-Unlike the other structures, <tt>rcu_dynticks</tt> is not
-replicated over the different flavors of RCU.
-The fields in this structure may be accessed only from the corresponding
-CPU (and from tracing) unless otherwise stated.
-Its fields are as follows:
+<p>
+This portion of the rcu_data structure is declared as follows:

<pre>
1 long dynticks_nesting;
2 long dynticks_nmi_nesting;
3 atomic_t dynticks;
4 bool rcu_need_heavy_qs;
- 5 unsigned long rcu_qs_ctr;
- 6 bool rcu_urgent_qs;
+ 5 bool rcu_urgent_qs;
</pre>

+<p>These fields in the rcu_data structure maintain the per-CPU dyntick-idle
+state for the corresponding CPU.
+The fields may be accessed only from the corresponding CPU (and from tracing)
+unless otherwise stated.
+
<p>The <tt>->dynticks_nesting</tt> field counts the
nesting depth of process execution, so that in normal circumstances
this counter has value zero or one.
@@ -1242,19 +1209,12 @@ it is willing to call for heavy-weight dyntick-counter operations.
This flag is checked by RCU's context-switch and <tt>cond_resched()</tt>
code, which provide a momentary idle sojourn in response.

-</p><p>The <tt>->rcu_qs_ctr</tt> field is used to record
-quiescent states from <tt>cond_resched()</tt>.
-Because <tt>cond_resched()</tt> can execute quite frequently, this
-must be quite lightweight, as in a non-atomic increment of this
-per-CPU field.
-
</p><p>Finally, the <tt>->rcu_urgent_qs</tt> field is used to record
-the fact that the RCU core code would really like to see a quiescent
-state from the corresponding CPU, with the various other fields indicating
-just how badly RCU wants this quiescent state.
-This flag is checked by RCU's context-switch and <tt>cond_resched()</tt>
-code, which, if nothing else, non-atomically increment <tt>->rcu_qs_ctr</tt>
-in response.
+the fact that the RCU core code would really like to see a quiescent state from
+the corresponding CPU, with the various other fields indicating just how badly
+RCU wants this quiescent state.
+This flag is checked by RCU's context-switch path
+(<tt>rcu_note_context_switch</tt>) and the cond_resched code.

<table>
<tr><th> </th></tr>
@@ -1431,7 +1391,7 @@ So each flavor of RCU is represented by an <tt>rcu_state</tt> structure,
which contains a combining tree of <tt>rcu_node</tt> and
<tt>rcu_data</tt> structures.
Finally, in <tt>CONFIG_NO_HZ_IDLE</tt> kernels, each CPU's dyntick-idle
-state is tracked by an <tt>rcu_dynticks</tt> structure.
+state is tracked by dynticks-related fields in the <tt>rcu_data</tt> structure.

If you made it this far, you are well prepared to read the code
walkthroughs in the other articles in this series.
--
2.17.1

Next message: Paul E. McKenney: "[PATCH tip/core/rcu 10/20] doc: rcu: Update core and full API in whatisRCU"
Previous message: Chris Packham: "Re: [PATCH v6 5/9] dt-bindings: ARM: document marvell,ecc-enable binding"
In reply to: Paul E. McKenney: "[PATCH tip/core/rcu 19/20] doc: Correct parameter in stallwarn"
Next in thread: Paul E. McKenney: "[PATCH tip/core/rcu 10/20] doc: rcu: Update core and full API in whatisRCU"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]