2016-10-28 16:14:32 +00:00
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From 6aa1eca98ca44f515e10d8058d0ff6db3c8a3c11 Mon Sep 17 00:00:00 2001
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From: Bogdan Hamciuc <bogdan.hamciuc@freescale.com>
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Date: Fri, 28 Sep 2012 17:04:33 +0300
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Subject: [PATCH 21/70] net: Make the netdev watchdog aware of hardware
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multiqueue devices
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If the netdev declares the NETIF_F_HW_ACCEL_MQ (accelerated multiqueue)
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capability, tell the watchdog to consider the per-netdev trans_start
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field rather than any individual multiqueue's timestamp. That is
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justified by the fact that queues only go in and out of congestion
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in groups, not individually, as far as the net device is concerned.
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Change-Id: I07a6693bf1f0bb1e9396c5e232452223a511ecc1
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Signed-off-by: Bogdan Hamciuc <bogdan.hamciuc@freescale.com>
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Reviewed-on: http://git.am.freescale.net:8181/1033
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Reviewed-by: Fleming Andrew-AFLEMING <AFLEMING@freescale.com>
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Tested-by: Fleming Andrew-AFLEMING <AFLEMING@freescale.com>
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---
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net/sched/sch_generic.c | 17 ++++++++++++++++-
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1 file changed, 16 insertions(+), 1 deletion(-)
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--- a/net/sched/sch_generic.c
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+++ b/net/sched/sch_generic.c
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2016-12-16 11:33:38 +00:00
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@@ -290,8 +290,23 @@ static void dev_watchdog(unsigned long a
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2016-10-28 16:14:32 +00:00
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txq = netdev_get_tx_queue(dev, i);
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/*
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* old device drivers set dev->trans_start
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+ *
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+ * (Actually, not only "old" devices, but also
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+ * those which perform queue management in a
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+ * separate hw accelerator. So even though the
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+ * net device itself is single-queued, it makes
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+ * sense (and is safe, too) to use kernel's
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+ * multiqueue interface, specifically to avoid
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+ * unnecessary device locking in SMP systems.
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+ * In this case, we ought to consider not an
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+ * individual txq's timestamp as a congestion
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+ * indicator, but the "old" per-netdev field.)
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*/
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- trans_start = txq->trans_start ? : dev->trans_start;
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+ if (dev->features & NETIF_F_HW_ACCEL_MQ)
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+ trans_start = dev->trans_start;
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+ else
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+ trans_start = txq->trans_start ? :
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+ dev->trans_start;
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if (netif_xmit_stopped(txq) &&
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time_after(jiffies, (trans_start +
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dev->watchdog_timeo))) {
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