Re: [PATCH 4/5] I/OAT: Tighten descriptor setup performance

From: Andrew Morton
Date: Wed Oct 17 2007 - 20:34:43 EST


On Wed, 17 Oct 2007 17:14:33 -0700
Shannon Nelson <shannon.nelson@xxxxxxxxx> wrote:

> The change to the async_tx interface cost this driver some performance by
> spreading the descriptor setup across several functions, including multiple
> passes over the new descriptor chain. Here we bring the work back into one
> primary function and only do one pass.
>
> Signed-off-by: Shannon Nelson <shannon.nelson@xxxxxxxxx>
> ---
>
> drivers/dma/ioat_dma.c | 170 +++++++++++++++++++++++++-----------------------
> drivers/dma/ioatdma.h | 6 +-
> 2 files changed, 93 insertions(+), 83 deletions(-)
>
> diff --git a/drivers/dma/ioat_dma.c b/drivers/dma/ioat_dma.c
> index c44f551..117ac38 100644
> --- a/drivers/dma/ioat_dma.c
> +++ b/drivers/dma/ioat_dma.c
> @@ -46,9 +46,12 @@
> /* internal functions */
> static void ioat_dma_start_null_desc(struct ioat_dma_chan *ioat_chan);
> static void ioat_dma_memcpy_cleanup(struct ioat_dma_chan *ioat_chan);
> +static inline struct ioat_desc_sw *ioat_dma_get_next_descriptor(
> + struct ioat_dma_chan *ioat_chan);

A forward-declared static inline is pretty weird. Does gcc actually do the
right thing with it?

This function is far too large to be inlined anyway.


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