From: Bob Copeland <me@bobcopeland.com>
To: Daniel J Blueman <daniel.blueman@gmail.com>
Cc: linville@tuxdriver.com, jirislaby@gmail.com, mickflemm@gmail.com,
lrodriguez@atheros.com, ath5k-devel@lists.ath5k.org,
linux-wireless@vger.kernel.org
Subject: Re: [ath5k-devel] [PATCH 4/5] ath5k: use rx hw descriptor pointer for self-linked check
Date: Wed, 15 Apr 2009 08:35:06 -0400 [thread overview]
Message-ID: <20090415123506.GA18774@hash.localnet> (raw)
In-Reply-To: <6278d2220904150520x2e385e66s146a3dc95db26e3c@mail.gmail.com>
On Wed, Apr 15, 2009 at 01:20:09PM +0100, Daniel J Blueman wrote:
> Just an observation: Each synchronous read over PCI will take at
> minimum 0.9us to return. Accessing tables in the host's cache
> hierarchy/memory will likely be much faster - possibly why it is done
> like this already.
>
> Is this a worthwhile tradeoff?
This is a good point -- but I think in this case, it is worth it
from a correctness rather than performance standpoint.
See http://lkml.org/lkml/2009/3/8/99 for why I think the current
code doesn't handle every case.
FWIW, madwifi does this too. We could eliminate it if we dropped the
self-linked buffer thing (but then we'd need to handle EOL interrupts).
--
Bob Copeland %% www.bobcopeland.com
next prev parent reply other threads:[~2009-04-15 12:36 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-15 11:57 [PATCH 0/5] misc ath5k fixes Bob Copeland
2009-04-15 11:57 ` [PATCH 1/5] ath5k: fix initvals errors Bob Copeland
2009-04-15 12:09 ` Nick Kossifidis
2009-04-15 11:57 ` [PATCH 2/5] ath5k: use tasklet_hi_schedule for beacon queue Bob Copeland
2009-04-15 12:11 ` Nick Kossifidis
2009-04-15 11:57 ` [PATCH 3/5] ath5k: use bool for modparams Bob Copeland
2009-04-15 12:11 ` Nick Kossifidis
2009-04-15 11:57 ` [PATCH 4/5] ath5k: use rx hw descriptor pointer for self-linked check Bob Copeland
2009-04-15 12:12 ` Nick Kossifidis
2009-04-15 12:20 ` [ath5k-devel] " Daniel J Blueman
2009-04-15 12:35 ` Bob Copeland [this message]
2009-04-15 11:57 ` [PATCH 5/5] ath5k: manipulate rxlink and descriptor address under rxbuf lock Bob Copeland
2009-04-15 12:13 ` Nick Kossifidis
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