49 lines
1.7 KiB
Diff
49 lines
1.7 KiB
Diff
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From 803e59362b6d94edff3a36f47a9da3e8dca4bde2 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
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<jeremie.galarneau@efficios.com>
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Date: Fri, 7 Dec 2018 17:06:39 -0500
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Subject: [PATCH 10/15] Fix: only wait if work queue is empty in real-time mode
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Unconditionally waiting for 10 ms after the completion of every batch
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of jobs of the work queue in real-time mode appears to be a behaviour
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inherited from the call-rcu thread.
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While this is a fair trade-off in the context of call-rcu, it is less
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evident that it is desirable in the context of a general-purpose
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work queue. Waiting when work is available artificially degrades the
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latency characteristics of the work queue.
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If a workqueue user even need the explicit delay for batching (e.g. if
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a call-rcu implementation would ever use the workqueue worker thread),
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it can add it within the worker_before_wait_fct callback received as
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argument from workqueue creation.
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Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
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Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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---
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src/workqueue.c | 5 ++++-
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1 file changed, 4 insertions(+), 1 deletion(-)
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diff --git a/src/workqueue.c b/src/workqueue.c
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index 39d0e07..14957a0 100644
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--- a/src/workqueue.c
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+++ b/src/workqueue.c
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@@ -246,7 +246,10 @@ static void *workqueue_thread(void *arg)
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cmm_smp_mb();
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}
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} else {
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- (void) poll(NULL, 0, 10);
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+ if (cds_wfcq_empty(&workqueue->cbs_head,
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+ &workqueue->cbs_tail)) {
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+ (void) poll(NULL, 0, 10);
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+ }
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}
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if (workqueue->worker_after_wake_up_fct)
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workqueue->worker_after_wake_up_fct(workqueue, workqueue->priv);
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--
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2.19.1
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