Re: [PATCH] swiotlb: fix dma_alloc_coherent allocation failureswith swiotlb

From: FUJITA Tomonori
Date: Thu Sep 04 2008 - 00:14:00 EST


On Thu, 04 Sep 2008 00:09:51 +0200
Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:

> Joerg Roedel <joerg.roedel@xxxxxxx> writes:
>
> > The SWIOTLB version of dma_alloc_coherent allocates all memory with
> > GFP_DMA unconditionally. This leads sometimes unnecessary to allocation
> > failures. This patch makes the allocation strategy to use the DMA32 zone
> > first if this is possible. The changes are boot tested on AMD64 and
> > compile tested for i386 and IA64.
>
> The high level dma_alloc_coherent() does that anyways.

The high level dma_alloc_coherent means the tricks in
arch/x86/pci-dma.c? If so, all the tricks has gone in tip/master.


> The swiotlb fallback really should only allocate from the swiotlb,
> nowhere else.

Agreed.

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