Re: [PATCH] scsi: ibmvscsi_tgt: Use dma_alloc_coherent() instead of get_zeroed_page/dma_map_single()

[Cai Huoqing]

On 11 10月 21 07:42:28, Christoph Hellwig wrote:
> On Mon, Oct 11, 2021 at 12:00:53AM +0800, Cai Huoqing wrote:
> > Replacing get_zeroed_page/free_page/dma_map_single/dma_unmap_single()
> > with dma_alloc_coherent/dma_free_coherent() helps to reduce
> > code size, and simplify the code, and coherent DMA will not
> > clear the cache every time.
> 
> This explanation does not make any sense whatsoever.  Please explain
> why it would an show numbers.
Hi Christoph,
thanks for your feedback.

In this case, just simplify the code.
10 insertions(+), 31 deletions(-)

dma_sync_ API is not called, I think the hardware may keep cache coherent
directly or is a no cache system. No need to make perfermance compare.

thanks
Cai