Messages in this thread Patch in this message | | | Date | Wed, 8 Apr 2020 14:21:12 -0700 (PDT) | From | David Rientjes <> | Subject | [rfc v2 6/6] dma-pool: scale the default DMA coherent pool size with memory capacity |
| |
When AMD memory encryption is enabled, some devices may use more than 256KB/sec from the atomic pools. It would be more appropriate to scale the default size based on memory capacity unless the coherent_pool option is used on the kernel command line.
This provides a slight optimization on initial expansion and is deemed appropriate due to the increased reliance on the atomic pools. Note that the default size of 128KB per pool will normally be larger than the single coherent pool implementation since there are now up to three coherent pools (DMA, DMA32, and kernel).
Alternatively, this could be done only when CONFIG_AMD_MEM_ENCRYPT is enabled.
Signed-off-by: David Rientjes <rientjes@google.com> --- kernel/dma/pool.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c index 6685ab89cfa7..42bac953548c 100644 --- a/kernel/dma/pool.c +++ b/kernel/dma/pool.c @@ -18,8 +18,8 @@ static struct gen_pool *atomic_pool_dma __ro_after_init; static struct gen_pool *atomic_pool_dma32 __ro_after_init; static struct gen_pool *atomic_pool_kernel __ro_after_init; -#define DEFAULT_DMA_COHERENT_POOL_SIZE SZ_256K -static size_t atomic_pool_size = DEFAULT_DMA_COHERENT_POOL_SIZE; +/* Size can be defined by the coherent_pool command line */ +static size_t atomic_pool_size; /* Dynamic background expansion when the atomic pool is near capacity */ static struct work_struct atomic_pool_work; @@ -132,6 +132,16 @@ static int __init dma_atomic_pool_init(void) { int ret = 0; + /* + * If coherent_pool was not used on the command line, default the pool + * sizes to 128KB per 1GB of memory, min 128KB, max MAX_ORDER-1. + */ + if (!atomic_pool_size) { + atomic_pool_size = max(totalram_pages() >> PAGE_SHIFT, 1UL) * + SZ_128K; + atomic_pool_size = min_t(size_t, atomic_pool_size, + 1 << (PAGE_SHIFT + MAX_ORDER-1)); + } INIT_WORK(&atomic_pool_work, atomic_pool_work_fn); atomic_pool_kernel = __dma_atomic_pool_init(atomic_pool_size,
| |