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net: rps: send out pending IPI's on CPU hotplug

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IPI's from the victim cpu are not handled in dev_cpu_callback.
So these pending IPI's would be sent to the remote cpu only when
NET_RX is scheduled on the victim cpu and since this trigger is
unpredictable it would result in packet latencies on the remote cpu.

This patch add support to send the pending ipi's of victim cpu.

Signed-off-by: Ashwanth Goli <ashwanth@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
ashwanth@codeaurora.org 2017-06-09 14:24:58 +05:30 committed by David S. Miller
parent 33d4c48213
commit 773fc8f6e8
1 changed files with 22 additions and 9 deletions
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31
net/core/dev.c
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@ -4949,6 +4949,19 @@ __sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
}
EXPORT_SYMBOL(__skb_gro_checksum_complete);
static void net_rps_send_ipi(struct softnet_data *remsd)
{
#ifdef CONFIG_RPS
while (remsd) {
struct softnet_data *next = remsd->rps_ipi_next;
if (cpu_online(remsd->cpu))
smp_call_function_single_async(remsd->cpu, &remsd->csd);
remsd = next;
}
#endif
}
/*
* net_rps_action_and_irq_enable sends any pending IPI's for rps.
* Note: called with local irq disabled, but exits with local irq enabled.
@ -4964,14 +4977,7 @@ static void net_rps_action_and_irq_enable(struct softnet_data *sd)
local_irq_enable();
/* Send pending IPI's to kick RPS processing on remote cpus. */
while (remsd) {
struct softnet_data *next = remsd->rps_ipi_next;
if (cpu_online(remsd->cpu))
smp_call_function_single_async(remsd->cpu,
&remsd->csd);
remsd = next;
}
net_rps_send_ipi(remsd);
} else
#endif
local_irq_enable();
@ -8197,7 +8203,7 @@ static int dev_cpu_dead(unsigned int oldcpu)
struct sk_buff **list_skb;
struct sk_buff *skb;
unsigned int cpu;
struct softnet_data *sd, *oldsd;
struct softnet_data *sd, *oldsd, *remsd;
local_irq_disable();
cpu = smp_processor_id();
@ -8238,6 +8244,13 @@ static int dev_cpu_dead(unsigned int oldcpu)
raise_softirq_irqoff(NET_TX_SOFTIRQ);
local_irq_enable();
#ifdef CONFIG_RPS
remsd = oldsd->rps_ipi_list;
oldsd->rps_ipi_list = NULL;
#endif
/* send out pending IPI's on offline CPU */
net_rps_send_ipi(remsd);
/* Process offline CPU's input_pkt_queue */
while ((skb = __skb_dequeue(&oldsd->process_queue))) {
netif_rx_ni(skb);