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From: Kalle Valo <kvalo@qca.qualcomm.com>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: linux-wireless@vger.kernel.org, ath10k@lists.infradead.org
Subject: Re: [PATCH v2 4/4] ath10k: fix issues on non-preemptible systems
Date: Tue, 27 Aug 2013 10:06:13 +0300	[thread overview]
Message-ID: <87ioyrmx3u.fsf@kamboji.qca.qualcomm.com> (raw)
In-Reply-To: <1377507205-5386-5-git-send-email-michal.kazior@tieto.com> (Michal Kazior's message of "Mon, 26 Aug 2013 10:53:25 +0200")

Michal Kazior <michal.kazior@tieto.com> writes:

> Workers may not call into a sleepable function
> (e.g. mutex_lock). Since ath10k workers can run
> for a very long time it is necessary to explicitly
> allow process rescheduling in case there's no
> preemption.
>
> This fixes some issues with system freezes, hangs,
> watchdogs being triggered, userspace being
> unresponsive on slow host machines under heavy
> load.

I consider this more as a workaround as a real fix. Would NAPI be a
proper fix for issues like this?

NAPI support was removed from mac80211 six months ago, but I guess we
could try to get it back if we have a good reason:

http://marc.info/?l=linux-wireless&m=136204135907491

> --- a/drivers/net/wireless/ath/ath10k/htt_rx.c
> +++ b/drivers/net/wireless/ath/ath10k/htt_rx.c
> @@ -1229,6 +1229,10 @@ static void ath10k_htt_rx_work(struct work_struct *work)
>  			break;
>  
>  		ath10k_htt_rx_process_skb(htt->ar, skb);
> +
> +#ifndef CONFIG_PREEMPT
> +		cond_resched();
> +#endif

Why the #ifndef? Why should we not call cond_resched() when PREEMPT is
enabled? Does something negative happen then?

-- 
Kalle Valo

_______________________________________________
ath10k mailing list
ath10k@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/ath10k

WARNING: multiple messages have this Message-ID (diff)
From: Kalle Valo <kvalo@qca.qualcomm.com>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: <ath10k@lists.infradead.org>, <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH v2 4/4] ath10k: fix issues on non-preemptible systems
Date: Tue, 27 Aug 2013 10:06:13 +0300	[thread overview]
Message-ID: <87ioyrmx3u.fsf@kamboji.qca.qualcomm.com> (raw)
In-Reply-To: <1377507205-5386-5-git-send-email-michal.kazior@tieto.com> (Michal Kazior's message of "Mon, 26 Aug 2013 10:53:25 +0200")

Michal Kazior <michal.kazior@tieto.com> writes:

> Workers may not call into a sleepable function
> (e.g. mutex_lock). Since ath10k workers can run
> for a very long time it is necessary to explicitly
> allow process rescheduling in case there's no
> preemption.
>
> This fixes some issues with system freezes, hangs,
> watchdogs being triggered, userspace being
> unresponsive on slow host machines under heavy
> load.

I consider this more as a workaround as a real fix. Would NAPI be a
proper fix for issues like this?

NAPI support was removed from mac80211 six months ago, but I guess we
could try to get it back if we have a good reason:

http://marc.info/?l=linux-wireless&m=136204135907491

> --- a/drivers/net/wireless/ath/ath10k/htt_rx.c
> +++ b/drivers/net/wireless/ath/ath10k/htt_rx.c
> @@ -1229,6 +1229,10 @@ static void ath10k_htt_rx_work(struct work_struct *work)
>  			break;
>  
>  		ath10k_htt_rx_process_skb(htt->ar, skb);
> +
> +#ifndef CONFIG_PREEMPT
> +		cond_resched();
> +#endif

Why the #ifndef? Why should we not call cond_resched() when PREEMPT is
enabled? Does something negative happen then?

-- 
Kalle Valo

  reply	other threads:[~2013-08-27  7:06 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-21  6:34 [PATCH 0/3] ath10k: fixes Michal Kazior
2013-08-21  6:34 ` Michal Kazior
2013-08-21  6:34 ` [PATCH 1/3] ath10k: make the workqueue multithreaded Michal Kazior
2013-08-21  6:34   ` Michal Kazior
2013-08-21  6:34 ` [PATCH 2/3] ath10k: move htt rx processing to worker Michal Kazior
2013-08-21  6:34   ` Michal Kazior
2013-08-21  6:34 ` [PATCH 3/3] ath10k: fix issues on non-preemptible systems Michal Kazior
2013-08-21  6:34   ` Michal Kazior
2013-08-22 10:05 ` [PATCH 0/3] ath10k: fixes Michal Kazior
2013-08-22 10:05   ` Michal Kazior
2013-08-26  8:53 ` [PATCH v2 0/4] " Michal Kazior
2013-08-26  8:53   ` Michal Kazior
2013-08-26  8:53   ` [PATCH v2 1/4] ath10k: synchronize tx/rx reporting to mac80211 Michal Kazior
2013-08-26  8:53     ` Michal Kazior
2013-08-28  4:23     ` Kalle Valo
2013-08-28  4:23       ` Kalle Valo
2013-08-28 10:54       ` Michal Kazior
2013-08-28 10:54         ` Michal Kazior
2013-08-28 11:04         ` Kalle Valo
2013-08-28 11:04           ` Kalle Valo
2013-08-26  8:53   ` [PATCH v2 2/4] ath10k: make the workqueue multithreaded Michal Kazior
2013-08-26  8:53     ` Michal Kazior
2013-08-26  8:53   ` [PATCH v2 3/4] ath10k: move htt rx processing to worker Michal Kazior
2013-08-26  8:53     ` Michal Kazior
2013-08-26  8:53   ` [PATCH v2 4/4] ath10k: fix issues on non-preemptible systems Michal Kazior
2013-08-26  8:53     ` Michal Kazior
2013-08-27  7:06     ` Kalle Valo [this message]
2013-08-27  7:06       ` Kalle Valo
2013-08-27  7:30       ` Michal Kazior
2013-08-27  7:30         ` Michal Kazior
2013-08-28  4:02         ` Kalle Valo
2013-08-28  4:02           ` Kalle Valo
2013-08-28 13:16           ` Michal Kazior
2013-08-28 13:16             ` Michal Kazior
2013-08-26 20:20   ` [PATCH v2 0/4] ath10k: fixes Luis R. Rodriguez
2013-08-26 20:20     ` Luis R. Rodriguez
2013-08-27  5:42     ` Michal Kazior
2013-08-27  5:42       ` Michal Kazior
2013-08-27  7:59       ` Luis R. Rodriguez
2013-08-27  7:59         ` Luis R. Rodriguez
2013-08-27  6:57     ` Kalle Valo
2013-08-27  6:57       ` Kalle Valo
2013-08-27  8:01       ` Luis R. Rodriguez
2013-08-27  8:01         ` Luis R. Rodriguez
2013-08-28  3:53         ` Kalle Valo
2013-08-28  3:53           ` Kalle Valo

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