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From: David Brownell <david-b@pacbell.net>
To: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>,
	linux-ide@vger.kernel.org,
	DaVinci <davinci-linux-open-source@linux.davincidsp.com>
Subject: Re: [patch 2.6.30-rc2 2/2] palm_bk3710:  UDMA performance fix
Date: Wed, 22 Apr 2009 13:32:24 -0700	[thread overview]
Message-ID: <200904221332.25200.david-b@pacbell.net> (raw)
In-Reply-To: <200904222026.11495.bzolnier@gmail.com>

On Wednesday 22 April 2009, Bartlomiej Zolnierkiewicz wrote:
> On Tuesday 21 April 2009 12:02:22 Sergei Shtylyov wrote:
> > David Brownell wrote:
> > 
> > > Fix UDMA throughput bug:  tCYC averages t2CYCTYP/2, but the code
> > > previously assumed it was the same as t2CYCTYP.
> > 
> >     Wow, thanks for finding it!
> > ....
> > 
> > > Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
> > 
> >     The patch itself is:
> > 
> > Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
> 
> applied

Thanks.  Further experimentation suggests (a) doing timing
computations in picoseconds, rather than nanoseconds, gives
better answers and makes that "slow" system faster by 25% or
more; and (b) increasing all the UDMA timings by one clock
cycle gives another few percent.

Now (a) makes obvious sense; but (b) seems odd ...

- Dave

  reply	other threads:[~2009-04-22 20:32 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-21  1:41 [patch 2.6.30-rc2 2/2] palm_bk3710: UDMA performance fix David Brownell
2009-04-21 10:02 ` Sergei Shtylyov
     [not found]   ` <49ED99AE.3020100-hkdhdckH98+B+jHODAdFcQ@public.gmane.org>
2009-04-21 10:28     ` David Brownell
2009-04-22 18:26   ` Bartlomiej Zolnierkiewicz
2009-04-22 20:32     ` David Brownell [this message]
     [not found]     ` <200904222026.11495.bzolnier-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2009-04-22 20:43       ` David Brownell
2009-04-22 21:05         ` Bartlomiej Zolnierkiewicz
     [not found]           ` <200904222305.54820.bzolnier-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2009-04-22 22:29             ` David Brownell
2009-04-23 20:48               ` Bartlomiej Zolnierkiewicz

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