[Skiboot] [PATCH] hw/phb3: Increase AIB TX command credit for DMA read in CAPP DMA mode

Andrew Donnellan andrew.donnellan at au1.ibm.com
Fri Jul 8 16:46:39 AEST 2016

On 08/07/16 16:40, Vaibhav Jain wrote:
> Hi Andrew,
> Andrew Donnellan <andrew.donnellan at au1.ibm.com> writes:
>> When enabling CAPI in DMA mode, set the AIB TX command credits for channel
>> 2 (DMA read) to 28, rather than 1. This significantly improves DMA read
>> performance in CAPI DMA mode.
> Any reason why you are only increasing command credits for DMA read on
> channel 2 and not for DMA writes on Channel 0 ?

As far as I'm aware we were only observing significant performance 
degradation on reads, not writes. John/Rick/Mike - thoughts?

Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan at au1.ibm.com  IBM Australia Limited

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