Messages in this thread | | | From | "Jiang, Dave" <> | Subject | Re: [RFC v2 1/2] PCI-Express Non-Transparent Bridge Support | Date | Wed, 1 Aug 2012 02:18:45 +0000 |
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On Jul 31, 2012, at 7:10 PM, "Jianbin Kang" <kjbmail@gmail.com> wrote:
>> Actually this is what I'm working on now, using async_tx to replace the >> memcpy. I believe the changes shouldn't be that significant. >> >> Is the "hardware that can setup dma" you refer to something that does >> not use this interface? >> > > Yes, they use this interface, but split 'memcpy_toio' to two operation: > 1. setup dma > 2. wait/poll for the dma to finish. > So maybe it need to provide a generic function 'tx' for different hardwares. > It's not worth it to do sync DMA. The performance is terrible.
> If async_tx is available, it's much better than this 'sync dma/memcpy'. > One problem with async_tx is, it can't detect memcpy error. > If the remote ntb goes down when async_memcpy is in operation, async_tx > will trigger an oops.
Yes that is something that needs to be addressed when we get async DMA support working.
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