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* [BUG] net: cpu offline cause napi stall
@ 2011-06-01 10:33 Frank Blaschka
  2011-06-01 12:13 ` Eric Dumazet
  0 siblings, 1 reply; 11+ messages in thread
From: Frank Blaschka @ 2011-06-01 10:33 UTC (permalink / raw)
  To: davem, eric.dumazet; +Cc: netdev, linux-s390, heiko.carstens

Hi Dave, Eric,

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. Do you think this could cause the stall or
did I miss something?

Thx for your help.

Frank


^ permalink raw reply	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2011-06-07  8:01 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-06-01 10:33 [BUG] net: cpu offline cause napi stall Frank Blaschka
2011-06-01 12:13 ` Eric Dumazet
2011-06-01 16:36   ` Heiko Carstens
2011-06-01 16:55     ` Eric Dumazet
2011-06-01 18:12       ` Heiko Carstens
2011-06-01 20:03         ` Eric Dumazet
2011-06-01 20:42           ` Heiko Carstens
2011-06-06 21:50             ` David Miller
2011-06-07  6:50               ` [PATCH] " Eric Dumazet
2011-06-07  7:09                 ` Eric Dumazet
2011-06-07  8:01                 ` David Miller

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