From: Johannes Berg <johannes@sipsolutions.net>
To: Ben Greear <greearb@candelatech.com>
Cc: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: 'ip' blocking for long time trying to down station
Date: Wed, 14 Nov 2012 10:14:51 +0100 [thread overview]
Message-ID: <1352884491.9510.2.camel@jlt4.sipsolutions.net> (raw)
In-Reply-To: <5091ADDD.4050407@candelatech.com> (sfid-20121101_000206_244719_62ADC7A2)
Hi Ben,
Sorry for the late reply.
> This is on the 400 station test machine. No more crashes, but I'm seeing long
> pauses (10+ seconds) when trying to down station interfaces (and sometimes other
> commands as well). The system cannot stabilize (my user-space app times out
> after a while due to blocking on system() calls such as the one below,
> and gives up, causing endless loops of up/down, associate, dhcp, etc)
> I'm going to tweak the user-space code more to try to bring up stations
> in smaller batches, but it still seems like there is room for improvement
> in the OS.
>
> Using sysrq, I got this trace of the command. I'm not sure it was blocked
> in the same place the whole time, but it seems likely. Any ideas for how
> to speed this sort of thing up?
>
> ./local/sbin/ip link set sta140 down
>
> [<ffffffff81070e2e>] flush_work+0x2b/0x34
> [<ffffffff8106f857>] ? cwq_dec_nr_in_flight+0x76/0x76
> [<ffffffffa026a673>] ieee80211_do_stop+0x379/0x544 [mac80211]
I'm guessing that the other interfaces are actually re-scheduling work
items while this is trying to flush ... I'm not really sure how to
improve this behaviour though.
johannes
next prev parent reply other threads:[~2012-11-14 9:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-31 23:01 'ip' blocking for long time trying to down station Ben Greear
2012-11-14 9:14 ` Johannes Berg [this message]
2012-11-14 17:13 ` Ben Greear
2012-11-14 17:28 ` Johannes Berg
2012-11-14 17:41 ` Ben Greear
2012-12-05 6:12 ` Ben Greear
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