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doc: proofread RCU guide

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Fixes: 64994b56cfd7 ("rcu: add RCU library supporting QSBR mechanism")
Cc: stable@dpdk.org

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
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Honnappa Nagarahalli 2019-10-08 16:12:14 -05:00 committed by David Marchand
parent fe56fe635b
commit 4831115f42
1 changed files with 12 additions and 12 deletions
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24
doc/guides/prog_guide/rcu_lib.rst
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@ -37,8 +37,8 @@ What is Quiescent State
-----------------------
Quiescent State can be defined as "any point in the thread execution where the
thread does not hold a reference to shared memory". It is up to the application
to determine its quiescent state.
thread does not hold a reference to shared memory". It is the responsibility of
the application to determine its quiescent state.
Let us consider the following diagram:
@ -76,7 +76,7 @@ Factors affecting the RCU mechanism
It is important to make sure that this library keeps the overhead of
identifying the end of grace period and subsequent freeing of memory,
to a minimum. The following explains how grace period and critical
to a minimum. The following paras explain how grace period and critical
section affect this overhead.
The writer has to poll the readers to identify the end of grace period.
@ -91,14 +91,14 @@ critical sections smaller requires additional CPU cycles (due to additional
reporting) in the readers.
Hence, we need the characteristics of a small grace period and large critical
section. This library addresses this by allowing the writer to do
other work without having to block until the readers report their quiescent
state.
section. This library addresses these characteristics by allowing the writer
to do other work without having to block until the readers report their
quiescent state.
RCU in DPDK
-----------
For DPDK applications, the start and end of a ``while(1)`` loop (where no
For DPDK applications, the beginning and end of a ``while(1)`` loop (where no
references to shared data structures are kept) act as perfect quiescent
states. This will combine all the shared data structure accesses into a
single, large critical section which helps keep the overhead on the
@ -106,11 +106,11 @@ reader side to a minimum.
DPDK supports a pipeline model of packet processing and service cores.
In these use cases, a given data structure may not be used by all the
workers in the application. The writer does not have to wait for all
the workers to report their quiescent state. To provide the required
flexibility, this library has a concept of a QS variable. The application
can create one QS variable per data structure to help it track the
end of grace period for each data structure. This helps keep the grace
workers in the application. The writer has to wait only for the workers that
use the data structure to report their quiescent state. To provide the required
flexibility, this library has a concept of a QS variable. If required, the
application can create one QS variable per data structure to help it track the
end of grace period for each data structure. This helps keep the length of grace
period to a minimum.
How to use this library