From: Jeff Garzik <jeff@garzik.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Linux IDE <linux-ide@vger.kernel.org>
Subject: Re: [PATCH] libata: Add MMIO support to pata_sil680
Date: Sun, 27 May 2007 22:21:05 -0400 [thread overview]
Message-ID: <465A3C91.7020002@garzik.org> (raw)
In-Reply-To: <20070525152028.05b79c83@the-village.bc.nu>
Alan Cox wrote:
> Correct, but it is also extremely slow. No point discussing fast paths
> for odd if() tests through the code when you burn 100nS unneccessarily
> every time you issue a command via PIO is there.
BTW if you wanna start PIO speed tuning, ISTR the device-select code
does not cache selections. We always unconditionally select a device
before a command in ata_qc_issue_prot(), IIRC.
ISTR for some cases this was intentional (following ATADRVR) but I bet
adding code to -not- select a device, if it is already selected, would
speed things up on slow PATA machines.
ata_qc_issue_prot() and ata_dev_select() would be starting points if
you're interested.
Jeff
next prev parent reply other threads:[~2007-05-28 2:21 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-15 6:12 [PATCH] libata: Add MMIO support to pata_sil680 Benjamin Herrenschmidt
2007-05-15 6:14 ` Benjamin Herrenschmidt
2007-05-23 13:42 ` Alan Cox
2007-05-23 22:48 ` Benjamin Herrenschmidt
2007-05-23 23:31 ` Alan Cox
2007-05-23 23:43 ` Benjamin Herrenschmidt
2007-05-24 0:13 ` Alan Cox
2007-05-24 3:42 ` Benjamin Herrenschmidt
2007-05-24 9:54 ` Alan Cox
2007-05-24 10:52 ` Jeff Garzik
2007-05-24 11:09 ` Alan Cox
2007-05-24 11:09 ` Jeff Garzik
2007-05-25 0:29 ` Jeff Garzik
2007-05-25 0:40 ` Alan Cox
2007-05-25 0:51 ` Jeff Garzik
2007-05-25 14:20 ` Alan Cox
2007-05-28 2:21 ` Jeff Garzik [this message]
2007-05-24 6:02 ` Jeff Garzik
2007-05-24 9:33 ` Alan Cox
2007-05-24 9:55 ` Jeff Garzik
2007-05-24 10:08 ` Benjamin Herrenschmidt
2007-05-24 20:56 ` Mark Lord
2007-05-24 22:52 ` Benjamin Herrenschmidt
2007-05-25 11:32 ` Mark Lord
2007-05-24 10:06 ` Benjamin Herrenschmidt
-- strict thread matches above, loose matches on Subject: below --
2008-02-12 15:58 Tim Ellis
2008-02-12 21:02 ` Benjamin Herrenschmidt
2008-02-12 21:42 ` Alan Cox
2008-02-15 15:52 ` Guennadi Liakhovetski
2008-02-15 15:53 ` Alan Cox
2008-02-15 21:45 ` Benjamin Herrenschmidt
2008-02-15 22:27 ` Alan Cox
2008-02-15 22:55 ` Benjamin Herrenschmidt
2008-02-15 23:56 ` Tim Ellis
2008-02-25 22:57 ` Jeff Garzik
2008-02-25 23:06 ` Guennadi Liakhovetski
2008-02-26 0:58 ` Benjamin Herrenschmidt
2008-02-15 21:36 ` Benjamin Herrenschmidt
2007-05-16 0:21 Benjamin Herrenschmidt
2007-05-16 12:05 ` Alan Cox
2007-05-16 12:12 ` Benjamin Herrenschmidt
2007-05-18 1:00 ` Jeff Garzik
2007-05-15 6:11 Benjamin Herrenschmidt
2007-05-15 6:14 ` Benjamin Herrenschmidt
2007-05-15 11:08 ` Alan Cox
2007-05-15 20:32 ` Benjamin Herrenschmidt
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