linux-kernel - Re: [ath9k-devel] ath9k: massive unexplained latency in 2.6.27 (rc5, rc6, probably others)

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Date:	Thu, 18 Sep 2008 11:34:03 -0700
From:	"Luis R. Rodriguez" <lrodriguez@...eros.com>
To:	"Steven Noonan" <steven@...inklabs.net>
Cc:	LKML <linux-kernel@...r.kernel.org>, "Ingo Molnar" <mingo@...e.hu>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	"ath9k-devel@...ts.ath9k.org" <ath9k-devel@...ts.ath9k.org>
Subject: Re: [ath9k-devel] ath9k: massive unexplained latency in 2.6.27 (rc5, rc6, probably others)

On Thu, Sep 18, 2008 at 11:23 AM, Steven Noonan <steven@...inklabs.net> wrote:
> The only thing I can think of is that I've
> got 'irqpoll' on the command line. I have it because I had to reload
> the ath9k driver at one point, and this was the result (caused ath9k
> to become a useless driver until I rebooted, which re-enabled IRQ 17):
>
> [53997.493777] ath9k: driver unloaded
> [54001.098532] ath9k: 0.1
> [54001.098833] ath9k 0000:03:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17
> [54001.099013] ath9k 0000:03:00.0: setting latency timer to 64
> [54001.233825] phy1: Selected rate control algorithm 'ath9k_rate_control'
> [54001.236980] phy1: Atheros 5416: mem=0xffffc20000060000, irq=17
> [54002.136218] irq 17: nobody cared (try booting with the "irqpoll" option)
> [54002.136229] Pid: 0, comm: swapper Tainted: P 2.6.27-rc6-00036-ga551b98 #2
> [54002.136234]
> [54002.136235] Call Trace:
> [54002.136241] <IRQ> [<ffffffff80265231>] __report_bad_irq+0x3d/0x81
> [54002.136258] [<ffffffff80265477>] note_interrupt+0x202/0x267
> [54002.136265] [<ffffffff80265bfc>] handle_fasteoi_irq+0xba/0xe4
> [54002.136273] [<ffffffff8020e7ff>] do_IRQ+0x115/0x191
> [54002.136279] [<ffffffff8020bc01>] ret_from_intr+0x0/0xa
> [54002.136283] <EOI> [<ffffffff802541bb>] ?
> tick_nohz_stop_sched_tick+0x2c5/0x2d4
> [54002.136296] [<ffffffff8020a69f>] ? cpu_idle+0x2d/0xed
> [54002.136304] [<ffffffff8060d741>] ? rest_init+0x75/0x77
> [54002.136309]
> [54002.136312] handlers:
> [54002.136315] [<ffffffffa0209016>] (ath_isr+0x0/0x160 [ath9k])
> [54002.136340] Disabling IRQ #17

irqpoll is a monster of evil and that should make your system crawl to
its knees. I would advise instead we work with you fixing the the
missed interrupts issue upon rmmod.

  Luis
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