From: Felix Fietkau <nbd@openwrt.org>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: linux-wireless@vger.kernel.org, linville@tuxdriver.com
Subject: Re: [PATCH 3/3] mac80211: optimize aggregation session timeout handling
Date: Sun, 18 Mar 2012 12:13:56 +0100 [thread overview]
Message-ID: <4F65C374.2060505@openwrt.org> (raw)
In-Reply-To: <1332065875.3609.3.camel@jlt3.sipsolutions.net>
On 2012-03-18 11:17 AM, Johannes Berg wrote:
> On Sun, 2012-03-18 at 00:00 +0100, Felix Fietkau wrote:
>> Calling mod_timer from the rx/tx hotpath is somewhat expensive, and the
>> timeout doesn't need to be so precise.
>>
>> Switch to a different strategy: Schedule the timer initially, store jiffies
>> of all last rx/tx activity which would previously modify the timer, and
>> let the timer re-arm itself after checking the last rx/tx timestamp.
>
> I don't like this. It's not the optimisation you think it is on other
> ("embedded") systems where firing a timer is more expensive.
>
> You're trading power consumption against CPU utilisation by causing the
> timer to wake up.
I considered that was well, but didn't think one wakeup every 5 seconds
or so would be significant. Would you take the patch if I change the
timer to be deferrable, so that it doesn't cause wakeups by itself?
- Felix
next prev parent reply other threads:[~2012-03-18 11:14 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-17 23:00 [PATCH 1/3] cfg80211: use compare_ether_addr on MAC addresses instead of memcmp Felix Fietkau
2012-03-17 23:00 ` [PATCH 2/3] mac80211: reduce code duplication in debugfs code Felix Fietkau
2012-03-17 23:00 ` [PATCH 3/3] mac80211: optimize aggregation session timeout handling Felix Fietkau
2012-03-18 10:17 ` Johannes Berg
2012-03-18 11:13 ` Felix Fietkau [this message]
2012-03-19 8:39 ` Johannes Berg
2012-03-19 9:29 ` Helmut Schaa
2012-03-19 9:39 ` Johannes Berg
2012-03-19 10:36 ` Felix Fietkau
2012-03-19 10:50 ` Helmut Schaa
2012-03-19 10:52 ` Felix Fietkau
2012-03-19 10:55 ` Helmut Schaa
2012-03-19 10:58 ` Felix Fietkau
2012-03-19 10:01 ` Felix Fietkau
2012-03-19 10:05 ` Johannes Berg
2012-03-19 10:34 ` Felix Fietkau
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