diff options
| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2011-06-06 20:50:03 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-06-07 01:01:22 -0700 |
| commit | 264524d5e5195f6e0f099bee20253a22b651e272 (patch) | |
| tree | bbb76f1a1f1ee31ff69d718443021576926f24cf | |
| parent | 6407d74c5106bb362b4087693688afd34942b094 (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>
| -rw-r--r-- | net/core/dev.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 1af6cb27f67..a54c9f87ddb 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(); |