Author: cognet
Date: Sun Aug 11 21:21:02 2013
New Revision: 254229
URL: http://svnweb.freebsd.org/changeset/base/254229
Log:
Only allocate 2 bounce pages for maps that can only use them for buffers that
are unaligned on cache lines boundary, as we will never need more.
Modified:
head/sys/arm/arm/busdma_machdep-v6.c
Modified: head/sys/arm/arm/busdma_machdep-v6.c
==============================================================================
--- head/sys/arm/arm/busdma_machdep-v6.c Sun Aug 11 21:15:04 2013
(r254228)
+++ head/sys/arm/arm/busdma_machdep-v6.c Sun Aug 11 21:21:02 2013
(r254229)
@@ -425,6 +425,8 @@ bus_dma_tag_create(bus_dma_tag_t parent,
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
* 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;
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