linux-kernel - [PATCH 05/23] sched,drbd: Convert to sched_set

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Message-Id: <20200422112831.515522261@infradead.org>
Date:   Wed, 22 Apr 2020 13:27:24 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     mingo@...nel.org, linux-kernel@...r.kernel.org
Cc:     tglx@...utronix.de, rostedt@...dmis.org, qais.yousef@....com,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, bsegall@...gle.com, mgorman@...e.de,
        peterz@...radead.org, axboe@...nel.dk
Subject: [PATCH 05/23] sched,drbd: Convert to sched_set_fifo*()

Because SCHED_FIFO is a broken scheduler model (see previous patches)
take away the priority field, the kernel can't possibly make an
informed decision.

In this case, use fifo_low, because it only cares about being above
SCHED_NORMAL. Effectively changes prio from 2 to 1.

Cc: axboe@...nel.dk
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Ingo Molnar <mingo@...nel.org>
---
 drivers/block/drbd/drbd_receiver.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -6020,9 +6020,8 @@ int drbd_ack_receiver(struct drbd_thread
 	unsigned int header_size = drbd_header_size(connection);
 	int expect   = header_size;
 	bool ping_timeout_active = false;
-	struct sched_param param = { .sched_priority = 2 };
 
-	rv = sched_setscheduler(current, SCHED_RR, &param);
+	rv = sched_set_fifo_low(current);
 	if (rv < 0)
 		drbd_err(connection, "drbd_ack_receiver: ERROR set priority, ret=%d\n", rv);