Re: [Qemu-devel] [RFC 1/2] pci-dma-api-v1

[Avi Kivity]

Blue Swirl wrote:
> The previous similar attempt by Anthony for generic DMA using vectored
> IO was abandoned because the malloc/free overhead was more than the
> performance gain. Have you made any performance measurements? How does
> this version compare to the previous ones?
>
>   

The pointers you gave don't blame malloc/free, instead the lack of aio 
readv/writev.

Since Andrea's patches contain emulation for aio readv/writev, the 
performance degradation will not occur (though we will not see the 
benefit either).

I doubt you can get measure malloc overhead with anything less a 
thousand disks (even there, other overheads are likely to drown that 
malloc).

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.