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Message-ID: <2a27d3730904270048g1e247797s6a25f9e28d664214@mail.gmail.com> Date: Mon, 27 Apr 2009 15:48:21 +0800 From: Li Yang <leoli@...escale.com> To: Ira Snyder <iws@...o.caltech.edu> Cc: linux-kernel@...r.kernel.org, Dan Williams <dan.j.williams@...el.com>, linuxppc-dev@...abs.org Subject: Re: [PATCH] fsldma: use PCI Read Multiple command On Sat, Apr 25, 2009 at 2:35 AM, Ira Snyder <iws@...o.caltech.edu> wrote: > By default, the Freescale 83xx DMA controller uses the PCI Read Line > command when reading data over the PCI bus. Setting the controller to use > the PCI Read Multiple command instead allows the controller to read much > larger bursts of data, which provides a drastic speed increase. > > The slowdown due to using PCI Read Line was only observed when a PCI-to-PCI > bridge was between the devices trying to communicate. > > A simple test driver showed an increase from 4MB/sec to 116MB/sec when > performing DMA over the PCI bus. Using DMA to transfer between blocks of > local SDRAM showed no change in performance with this patch. The dmatest > driver was also used to verify the correctness of the transfers, and showed > no errors. > > Signed-off-by: Ira W. Snyder <iws@...o.caltech.edu> Acked-by: Li Yang <leoli@...escale.com> Thanks, Leo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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