From: "John W. Linville" <linville@tuxdriver.com>
To: Nathaniel Smith <njs@pobox.com>
Cc: linux-wireless@vger.kernel.org,
bloat-devel@lists.bufferbloat.net, johannes@sipsolutions.net,
nbd@openwrt.org
Subject: Re: [RFC v2] mac80211: implement eBDP algorithm to fight bufferbloat
Date: Mon, 21 Feb 2011 13:47:17 -0500 [thread overview]
Message-ID: <20110221184716.GD9650@tuxdriver.com> (raw)
In-Reply-To: <AANLkTikJeN=CG20PAj-n1ZoaiJLbsiG=jfZnbu4Or3KS@mail.gmail.com>
On Fri, Feb 18, 2011 at 07:44:30PM -0800, Nathaniel Smith wrote:
> On Fri, Feb 18, 2011 at 1:21 PM, John W. Linville
> <linville@tuxdriver.com> wrote:
> > + /* grab timestamp info for buffer control estimates */
> > + tserv = ktime_sub(ktime_get(), skb->tstamp);
> [...]
> > + ewma_add(&sta->sdata->qdata[q].tserv_ns_avg,
> > + ktime_to_ns(tserv));
>
> I think you're still measuring how long it takes one packet to get
> from the end of the queue to the beginning, rather than measuring how
> long it takes each packet to go out?
Yes, I am measuring how long the driver+device takes to release each
skb back to me (using that as a proxy for how long it takes to get
the fragment to the next hop). Actually, FWIW I'm only measuring
that time for those skb's that result in a tx status report.
I tried to see how your measurement would be useful, but I just don't
see how the number of frames ahead of me in the queue is relevant to
the measured link latency? I mean, I realize that having more packets
ahead of me in the queue is likely to increase the latency for this
frame, but I don't understand why I should use that information to
discount the measured latency...?
John
--
John W. Linville Someday the world will need a hero, and you
linville@tuxdriver.com might be all we have. Be ready.
next prev parent reply other threads:[~2011-02-21 19:00 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
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 [this message]
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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