From: Mateusz Nosek <mateusznosek0@xxxxxxxxx> Subject: mm/dmapool.c: micro-optimisation remove unnecessary branch Previously there was a check if 'size' is aligned to 'align' and if not then it was aligned. This check was expensive as both branch and division are expensive instructions in most architectures. 'ALIGN' function on already aligned value will not change it, and as it is cheaper than branch + division it can be executed all the time and branch can be removed. Link: http://lkml.kernel.org/r/20200320173317.26408-1-mateusznosek0@xxxxxxxxx Signed-off-by: Mateusz Nosek <mateusznosek0@xxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/dmapool.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) --- a/mm/dmapool.c~mm-dmapoolc-micro-optimisation-remove-unnecessary-branch +++ a/mm/dmapool.c @@ -144,9 +144,7 @@ struct dma_pool *dma_pool_create(const c else if (size < 4) size = 4; - if ((size % align) != 0) - size = ALIGN(size, align); - + size = ALIGN(size, align); allocation = max_t(size_t, size, PAGE_SIZE); if (!boundary) _
