From: Frank Blaschka <blaschka@linux.vnet.ibm.com>
To: davem@davemloft.net, eric.dumazet@gmail.com
Cc: netdev@vger.kernel.org, linux-s390@vger.kernel.org,
heiko.carstens@de.ibm.com
Subject: [BUG] net: cpu offline cause napi stall
Date: Wed, 1 Jun 2011 12:33:56 +0200 [thread overview]
Message-ID: <20110601103356.GA45482@tuxmaker.boeblingen.de.ibm.com> (raw)
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
next reply other threads:[~2011-06-01 10:34 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-01 10:33 Frank Blaschka [this message]
2011-06-01 12:13 ` [BUG] net: cpu offline cause napi stall 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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