Currently a call to dma_pool_alloc() with a ___GFP_ZERO flag returns
a non-zeroed memory region.
This patchset adds support for the __GFP_ZERO flag to dma_pool_alloc(),
adds 2 wrapper functions for allocing zeroed memory from a pool,
and provides a coccinelle script for finding & replacing instances of
dma_pool_alloc() followed by memset(0) with a single dma_pool_zalloc() call.
Changes from v1 to v2:
- don't memset() POOL_POISON_ALLOCATED in dma_pool_alloc() if
__GFP_ZERO is set
- Ran test to see how often pool_alloc_page() is called
There was some concern that this always calls memset() to zero,
instead of passing __GFP_ZERO into the page allocator.
[https://lkml.org/lkml/2015/7/15/881]
I ran a test on my system to get an idea of how often dma_pool_alloc()
calls into pool_alloc_page().
After Boot: [ 30.119863] alloc_calls:541, page_allocs:7
After an hour: [ 3600.951031] alloc_calls:9566, page_allocs:12
After copying 1GB file onto a USB drive:
[ 4260.657148] alloc_calls:17225, page_allocs:12
It doesn't look like dma_pool_alloc() calls down to the page allocator
very often (at least on my system).
Sean O. Stalley (4):
mm: Add support for __GFP_ZERO flag to dma_pool_alloc()
mm: Add dma_pool_zalloc() call to DMA API
pci: mm: Add pci_pool_zalloc() call
coccinelle: mm: scripts/coccinelle/api/alloc/pool_zalloc-simple.cocci
Documentation/DMA-API.txt | 7 ++
include/linux/dmapool.h | 6 ++
include/linux/pci.h | 2 +
mm/dmapool.c | 9 ++-
.../coccinelle/api/alloc/pool_zalloc-simple.cocci | 84 ++++++++++++++++++++++
5 files changed, 106 insertions(+), 2 deletions(-)
create mode 100644 scripts/coccinelle/api/alloc/pool_zalloc-simple.cocci
--
1.9.1
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
