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76 lines
2.7 KiB
Diff
76 lines
2.7 KiB
Diff
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From 56364c910691f6d10ba88c964c9041b9ab777bd6 Mon Sep 17 00:00:00 2001
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Mon, 25 Mar 2024 08:40:28 +0100
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Subject: [PATCH 1/4] net: Remove conditional threaded-NAPI wakeup based on
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task state.
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A NAPI thread is scheduled by first setting NAPI_STATE_SCHED bit. If
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successful (the bit was not yet set) then the NAPI_STATE_SCHED_THREADED
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is set but only if thread's state is not TASK_INTERRUPTIBLE (is
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TASK_RUNNING) followed by task wakeup.
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If the task is idle (TASK_INTERRUPTIBLE) then the
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NAPI_STATE_SCHED_THREADED bit is not set. The thread is no relying on
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the bit but always leaving the wait-loop after returning from schedule()
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because there must have been a wakeup.
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The smpboot-threads implementation for per-CPU threads requires an
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explicit condition and does not support "if we get out of schedule()
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then there must be something to do".
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Removing this optimisation simplifies the following integration.
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Set NAPI_STATE_SCHED_THREADED unconditionally on wakeup and rely on it
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in the wait path by removing the `woken' condition.
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Acked-by: Jakub Kicinski <kuba@kernel.org>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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---
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net/core/dev.c | 14 ++------------
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1 file changed, 2 insertions(+), 12 deletions(-)
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--- a/net/core/dev.c
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+++ b/net/core/dev.c
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@@ -4473,13 +4473,7 @@ static inline void ____napi_schedule(str
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*/
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thread = READ_ONCE(napi->thread);
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if (thread) {
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- /* Avoid doing set_bit() if the thread is in
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- * INTERRUPTIBLE state, cause napi_thread_wait()
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- * makes sure to proceed with napi polling
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- * if the thread is explicitly woken from here.
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- */
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- if (READ_ONCE(thread->__state) != TASK_INTERRUPTIBLE)
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- set_bit(NAPI_STATE_SCHED_THREADED, &napi->state);
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+ set_bit(NAPI_STATE_SCHED_THREADED, &napi->state);
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wake_up_process(thread);
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return;
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}
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@@ -6635,8 +6629,6 @@ static int napi_poll(struct napi_struct
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static int napi_thread_wait(struct napi_struct *napi)
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{
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- bool woken = false;
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-
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set_current_state(TASK_INTERRUPTIBLE);
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while (!kthread_should_stop()) {
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@@ -6645,15 +6637,13 @@ static int napi_thread_wait(struct napi_
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* Testing SCHED bit is not enough because SCHED bit might be
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* set by some other busy poll thread or by napi_disable().
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*/
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- if (test_bit(NAPI_STATE_SCHED_THREADED, &napi->state) || woken) {
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+ if (test_bit(NAPI_STATE_SCHED_THREADED, &napi->state)) {
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WARN_ON(!list_empty(&napi->poll_list));
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__set_current_state(TASK_RUNNING);
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return 0;
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}
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schedule();
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- /* woken being true indicates this thread owns this napi. */
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- woken = true;
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set_current_state(TASK_INTERRUPTIBLE);
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}
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__set_current_state(TASK_RUNNING);
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