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From: Johannes Berg <johannes@sipsolutions.net>
To: "Nathaniel J. Smith" <njs@pobox.com>
Cc: linville@tuxdriver.com, linux-wireless@vger.kernel.org,
	wey-yi.w.guy@intel.com, ilw@linux.intel.com
Subject: Re: [PATCH 1/5] iwlwifi: Simplify tx queue management
Date: Mon, 14 Feb 2011 10:57:33 +0100	[thread overview]
Message-ID: <1297677453.3785.4.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <1297619803-2832-2-git-send-email-njs@pobox.com>

On Sun, 2011-02-13 at 09:56 -0800, Nathaniel J. Smith wrote:
> Previously, the iwlwifi driver filled its transmit queue until it
> reached a high-water mark, and then stopped until it had fallen to a
> low-water mark. This basic logic makes sense for interrupt mitigation
> -- you might not want to wake up the CPU after every packet, but
> instead wait until a batch of packets has been sent -- except the
> iwlwifi driver doesn't actually do any interrupt mitigation; the CPU
> wakes up after every packet transmitted anyway. So we simplify the
> code to maintain only a single limit on total queue length, and
> whenever we drop below that limit we allow more packets in.
> 
> This patch should have no user-visible effect.

I'm pretty sure the devices (but maybe not 3945) implement interrupt
mitigation at least in some cases. How did you arrive at the conclusion
that "the driver doesn't actually do any interrupt mitigation"?

johannes



  reply	other threads:[~2011-02-14  9:57 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-13 17:56 [PATCH 0/5] iwlwifi: Auto-tune tx queue size to maintain latency under load Nathaniel J. Smith
2011-02-13 17:56 ` [PATCH 1/5] iwlwifi: Simplify tx queue management Nathaniel J. Smith
2011-02-14  9:57   ` Johannes Berg [this message]
2011-02-14 22:17     ` Nathaniel Smith
2011-02-14 22:45       ` wwguy
2011-02-15  0:15         ` Dave Täht
2011-02-16  9:16         ` Stanislaw Gruszka
2011-02-16 14:41           ` John W. Linville
2011-02-16 15:13             ` wwguy
2011-02-15 12:11       ` Johannes Berg
2011-02-14 15:33   ` wwguy
2011-02-13 17:56 ` [PATCH 2/5] iwlwifi: Convert the tx queue high_mark to an atomic_t Nathaniel J. Smith
2011-02-14 12:16   ` Johannes Berg
2011-02-14 22:35     ` Nathaniel Smith
2011-02-15 12:08       ` Johannes Berg
2011-02-15 17:37         ` Nathaniel Smith
2011-02-13 17:56 ` [PATCH 3/5] iwlwifi: Invert the sense of the queue high_mark Nathaniel J. Smith
2011-02-13 17:56 ` [PATCH 4/5] iwlwifi: auto-tune tx queue size to minimize latency Nathaniel J. Smith
2011-02-14 12:17   ` Johannes Berg
2011-02-14 21:58     ` Nathaniel Smith
2011-02-15 12:13       ` Johannes Berg
2011-02-15 15:03         ` John W. Linville
2011-02-16  8:59           ` Johannes Berg
2011-02-15 17:31         ` Nathaniel Smith
2011-02-14 15:46   ` wwguy
2011-02-13 17:56 ` [PATCH 5/5] iwlwifi: make current tx queue sizes visible in debugfs Nathaniel J. Smith
2011-02-14  0:32 ` [PATCH 0/5] iwlwifi: Auto-tune tx queue size to maintain latency under load Julian Calaby
2011-02-14  3:28   ` Nathaniel Smith
2011-02-16 15:50 ` John W. Linville
2011-02-16 23:08   ` Nathaniel Smith
2011-02-16 23:42     ` wwguy
2011-02-17  1:49 ` [RFC] mac80211: implement eBDP algorithm to fight bufferbloat John W. Linville
2011-02-17  3:31   ` Ben Greear
2011-02-17  4:26   ` Nathaniel Smith
2011-02-17  8:31   ` Johannes Berg
2011-02-18 21:21   ` [RFC v2] " John W. Linville
2011-02-19  3:44     ` Nathaniel Smith
2011-02-21 18:47       ` John W. Linville
2011-02-21 23:26         ` Nathaniel Smith
2011-02-23 22:28           ` John W. Linville
2011-02-25 18:21             ` Nathaniel Smith
2011-02-25 18:27               ` Nathaniel Smith
2011-02-20  0:37     ` Nathaniel Smith
2011-02-21 18:52       ` John W. Linville
2011-02-21 15:28     ` Johannes Berg
2011-02-21 19:06       ` John W. Linville
2011-02-21 20:26         ` Tianji Li
2011-02-28 13:07         ` Johannes Berg

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