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From: Nathaniel Smith <njs@pobox.com>
To: Julian Calaby <julian.calaby@gmail.com>
Cc: linville@tuxdriver.com, linux-wireless@vger.kernel.org,
	wey-yi.w.guy@intel.com, ilw@linux.intel.com
Subject: Re: [PATCH 0/5] iwlwifi: Auto-tune tx queue size to maintain latency under load
Date: Sun, 13 Feb 2011 19:28:51 -0800	[thread overview]
Message-ID: <AANLkTin6yoJcC+nPHPs=wWBptUu7pCu3ctdn+EdP7uS3@mail.gmail.com> (raw)
In-Reply-To: <AANLkTin4MkMrz6Aa7g6JrB+QsNRHFvc26MFQ4UzcUM_L@mail.gmail.com>

On Sun, Feb 13, 2011 at 4:32 PM, Julian Calaby <julian.calaby@gmail.com> wrote:
> The short term solution (but not an overall solution by any means) is
> to reduce these buffers so that packets are dropped when links are
> congested.

The job of a device transmit buffer is just to couple the "real"
generic networking layer buffer, where QoS, AQM, etc. are applied, to
the network hardware. They should just be as small as is consistent
with reasonable CPU utilization and throughput. There are many
different problems with over-large buffers, but this particular one is
very simple.

>> This patch series teaches the driver to measure the average rate of
>> packet transmission for each tx queue, and adjusts the queue size
>> dynamically in an attempt to achieve ~2 ms of added latency.
>
> IMHO, I'm not sure that this is the best method of implementing this
> solution: most wireless (and ethernet) devices have some form of
> buffer for the same reason, so implementing a solution for iwlwifi is
> not an overall solution - we need some method of doing this for *all*
> network devices, not just iwlwifi.

I agree, but I figure a good start is a good start, and at least it
scratches my itch. Maybe the other driver developers will move faster
once iwlwifi starts showing them up ;-).

-- Nathaniel

  reply	other threads:[~2011-02-14  3:28 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
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 [this message]
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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