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From: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
To: honnappa.nagarahalli@arm.com, konstantin.ananyev@intel.com
Cc: dev@dpdk.org, stable@dpdk.org
Subject: [dpdk-stable] [PATCH 3/7] doc/rcu: add information about storing token and resource
Date: Sun,  8 Sep 2019 17:49:45 -0500
Message-ID: <20190908224949.34851-4-honnappa.nagarahalli@arm.com> (raw)
In-Reply-To: <20190908224949.34851-1-honnappa.nagarahalli@arm.com>

After calling rte_rcu_qsbr_start API, the token and the deleted
resource need to be stored for subsequent query/free.

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

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
---
 doc/guides/prog_guide/rcu_lib.rst | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/doc/guides/prog_guide/rcu_lib.rst b/doc/guides/prog_guide/rcu_lib.rst
index 4d1ed3954..8d0dfcf29 100644
--- a/doc/guides/prog_guide/rcu_lib.rst
+++ b/doc/guides/prog_guide/rcu_lib.rst
@@ -162,14 +162,19 @@ running as worker threads.
 The separation of triggering the reporting from querying the status provides
 the writer threads flexibility to do useful work instead of blocking for the
 reader threads to enter the quiescent state or go offline. This reduces the
-memory accesses due to continuous polling for the status.
+memory accesses due to continuous polling for the status. But, since the
+resource is freed at a later time, the token and the reference to the deleted
+resource need to be stored for later queries.
 
 The ``rte_rcu_qsbr_synchronize()`` API combines the functionality of
 ``rte_rcu_qsbr_start()`` and blocking ``rte_rcu_qsbr_check()`` into a single
 API. This API triggers the reader threads to report their quiescent state and
 polls till all the readers enter the quiescent state or go offline. This API
 does not allow the writer to do useful work while waiting and introduces
-additional memory accesses due to continuous polling.
+additional memory accesses due to continuous polling. However, the application
+does not have to store the token or the reference to the deleted resource. The
+resource can be freed immediately after ``rte_rcu_qsbr_synchronize()`` API
+returns.
 
 The reader thread must call ``rte_rcu_qsbr_thread_offline()`` and
 ``rte_rcu_qsbr_thread_unregister()`` APIs to remove itself from reporting its
-- 
2.17.1


  parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190908224949.34851-1-honnappa.nagarahalli@arm.com>
2019-09-08 22:49 ` [dpdk-stable] [PATCH 1/7] doc/rcu: fix typos Honnappa Nagarahalli
2019-09-08 22:49 ` [dpdk-stable] [PATCH 2/7] doc/rcu: correct the limitation on number of threads Honnappa Nagarahalli
2019-09-08 22:49 ` Honnappa Nagarahalli [this message]
2019-09-08 22:49 ` [dpdk-stable] [PATCH 4/7] test/rcu: use size_t instead of int Honnappa Nagarahalli
2019-09-09 15:16   ` [dpdk-stable] [dpdk-dev] " Ruifeng Wang (Arm Technology China)
2019-10-07 14:00     ` David Marchand
2019-09-08 22:49 ` [dpdk-stable] [PATCH 6/7] lib/rcu: add least acknowledged token optimization Honnappa Nagarahalli

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