NVMe: Optimise memory usage for I/Os between 4k and 128k
Add a second memory pool for smaller I/Os. We can pack 16 of these on a
single page instead of using an entire page for each one.
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c
index 80fe6a7..cd7aeba 100644
--- a/drivers/block/nvme.c
+++ b/drivers/block/nvme.c
@@ -58,6 +58,7 @@
u32 __iomem *dbs;
struct pci_dev *pci_dev;
struct dma_pool *prp_page_pool;
+ struct dma_pool *prp_small_pool;
int instance;
int queue_count;
u32 ctrl_config;
@@ -249,11 +250,6 @@
return 0;
}
-static __le64 *alloc_prp_list(struct nvme_dev *dev, dma_addr_t *addr)
-{
- return dma_pool_alloc(dev->prp_page_pool, GFP_ATOMIC, addr);
-}
-
struct nvme_prps {
int npages;
dma_addr_t first_dma;
@@ -271,6 +267,9 @@
return;
prp_dma = prps->first_dma;
+
+ if (prps->npages == 0)
+ dma_pool_free(dev->prp_small_pool, prps->list[0], prp_dma);
for (i = 0; i < prps->npages; i++) {
__le64 *prp_list = prps->list[i];
dma_addr_t next_prp_dma = le64_to_cpu(prp_list[last_prp]);
@@ -322,6 +321,7 @@
struct scatterlist *sg, int length)
{
struct nvme_dev *dev = nvmeq->dev;
+ struct dma_pool *pool;
int dma_len = sg_dma_len(sg);
u64 dma_addr = sg_dma_address(sg);
int offset = offset_in_page(dma_addr);
@@ -352,9 +352,16 @@
nprps = DIV_ROUND_UP(length, PAGE_SIZE);
npages = DIV_ROUND_UP(8 * nprps, PAGE_SIZE);
prps = kmalloc(sizeof(*prps) + sizeof(__le64 *) * npages, GFP_ATOMIC);
- prps->npages = npages;
prp_page = 0;
- prp_list = alloc_prp_list(dev, &prp_dma);
+ if (nprps <= (256 / 8)) {
+ pool = dev->prp_small_pool;
+ prps->npages = 0;
+ } else {
+ pool = dev->prp_page_pool;
+ prps->npages = npages;
+ }
+
+ prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma);
prps->list[prp_page++] = prp_list;
prps->first_dma = prp_dma;
cmd->prp2 = cpu_to_le64(prp_dma);
@@ -362,7 +369,7 @@
for (;;) {
if (i == PAGE_SIZE / 8 - 1) {
__le64 *old_prp_list = prp_list;
- prp_list = alloc_prp_list(dev, &prp_dma);
+ prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma);
prps->list[prp_page++] = prp_list;
old_prp_list[i] = cpu_to_le64(prp_dma);
i = 0;
@@ -1313,12 +1320,20 @@
if (!dev->prp_page_pool)
return -ENOMEM;
+ /* Optimisation for I/Os between 4k and 128k */
+ dev->prp_small_pool = dma_pool_create("prp list 256", dmadev,
+ 256, 256, 0);
+ if (!dev->prp_small_pool) {
+ dma_pool_destroy(dev->prp_page_pool);
+ return -ENOMEM;
+ }
return 0;
}
static void nvme_release_prp_pools(struct nvme_dev *dev)
{
dma_pool_destroy(dev->prp_page_pool);
+ dma_pool_destroy(dev->prp_small_pool);
}
/* XXX: Use an ida or something to let remove / add work correctly */