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Only allocate 2 bounce pages for maps that can only use them for buffers that

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are unaligned on cache lines boundary, as we will never need more.
This commit is contained in:
Olivier Houchard 2013-08-11 21:21:02 +00:00
parent 6006884122
commit ae8ab0e2c4
1 changed files with 6 additions and 1 deletions
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7
sys/arm/arm/busdma_machdep-v6.c
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@ -425,6 +425,8 @@ bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
if (_bus_dma_can_bounce(newtag->lowaddr, newtag->highaddr)
|| newtag->alignment > 1)
newtag->flags |= BUS_DMA_COULD_BOUNCE;
else
maxsize = 2; /* Need at most 2 bounce pages for unaligned access on cache line boundaries */
if ((flags & BUS_DMA_ALLOCNOW) != 0) {
struct bounce_zone *bz;
@ -519,7 +521,10 @@ static int allocate_bz_and_pages(bus_dma_tag_t dmat, bus_dmamap_t mapp)
* Attempt to add pages to our pool on a per-instance
* basis up to a sane limit.
*/
maxpages = MAX_BPAGES;
if (dmat->flags & BUS_DMA_COULD_BOUNCE)
maxpages = MAX_BPAGES;
else
maxpages = 2 * bz->map_count; /* Only need at most 2 pages for buffers unaligned on cache line boundaries */
if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0
|| (bz->map_count > 0 && bz->total_bpages < maxpages)) {
int pages;