From: Michael Moese <michael.moese@men.de>
To: David Laight <David.Laight@ACULAB.COM>
Cc: "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
David Hawkins <dwh@ovro.caltech.edu>,
'Michael Moese' <michael.moese@men.de>
Subject: Re: PCIe Access - achieve bursts without DMA
Date: Mon, 3 Feb 2014 11:39:44 +0100 [thread overview]
Message-ID: <20140203103943.GC1970@localhost.intra.men.de> (raw)
In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D0F6B774B@AcuExch.aculab.com>
On Mon, Feb 03, 2014 at 10:17:43AM +0000, David Laight wrote:
> We achieved about twice that using the PEX dma controller.
> Your 3MB/s for single word transfers is similar to what we saw.
> Cycle times that make an ISA bus look fast.
Indeed, this is a really poor performance. I know we could achieve much
more performance using DMA, we have several products where we simply
don't have DMA available - this requires searching for other paths.
My ioremap_wt() could help in these situations, at least increasing
performance for non-DMA operation to a not-that-bad level.
I don't know if other devices could benefit from this, but surely we
got several IPs that would, but those were not yet upstreamed, we're
still working on this.
Michael
next prev parent reply other threads:[~2014-02-03 10:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-30 12:20 PCIe Access - achieve bursts without DMA Moese, Michael
2014-01-30 14:19 ` David Laight
2014-01-31 12:31 ` Gabriel Paubert
2014-01-31 22:53 ` Benjamin Herrenschmidt
2014-01-31 23:18 ` David Hawkins
2014-02-03 8:20 ` Michael Moese
2014-02-03 10:17 ` David Laight
2014-02-03 10:39 ` Michael Moese [this message]
2014-02-03 10:51 ` David Laight
2014-02-03 17:08 ` David Hawkins
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