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authorHeiko Carstens <heiko.carstens@de.ibm.com>2011-06-06 20:50:03 +0000
committerDavid S. Miller <davem@davemloft.net>2011-06-07 01:01:22 -0700
commit264524d5e5195f6e0f099bee20253a22b651e272 (patch)
treebbb76f1a1f1ee31ff69d718443021576926f24cf /net
parent6407d74c5106bb362b4087693688afd34942b094 (diff)
net: cpu offline cause napi stall
Frank Blaschka reported : <quote> During heavy network load we turn off/on cpus. Sometimes this causes a stall on the network device. Digging into the dump I found out following: napi is scheduled but does not run. From the I/O buffers and the napi state I see napi/rx_softirq processing has stopped because the budget was reached. napi stays in the softnet_data poll_list and the rx_softirq was raised again. I assume at this time the cpu offline comes in, the rx softirq is raised/moved to another cpu but napi stays in the poll_list of the softnet_data of the now offline cpu. Reviewing dev_cpu_callback (net/core/dev.c) I did not find the poll_list is transfered to the new cpu. </quote> This patch is a straightforward implementation of Frank suggestion : Transfert poll_list and trigger NET_RX_SOFTIRQ on new cpu. Reported-by: Frank Blaschka <blaschka@linux.vnet.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Tested-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/dev.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 1af6cb27f67a..a54c9f87ddbb 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6178,6 +6178,11 @@ static int dev_cpu_callback(struct notifier_block *nfb,
oldsd->output_queue = NULL;
oldsd->output_queue_tailp = &oldsd->output_queue;
}
+ /* Append NAPI poll list from offline CPU. */
+ if (!list_empty(&oldsd->poll_list)) {
+ list_splice_init(&oldsd->poll_list, &sd->poll_list);
+ raise_softirq_irqoff(NET_RX_SOFTIRQ);
+ }
raise_softirq_irqoff(NET_TX_SOFTIRQ);
local_irq_enable();