[PATCH v8 06/12] mmc: mmc_test: test to measure how sg_len affect performance

test that measures how the mmc bandwidth depends on the numbers of sg elements
in the sg list. The transfer size if fixed and sg length goes from a few up
to 512. The purpose is to measure overhead caused by multiple sg elements.

Signed-off-by: Per Forlin <redacted>
---
?drivers/mmc/card/mmc_test.c | ?151 +++++++++++++++++++++++++++++++++++++++----
?1 files changed, 139 insertions(+), 12 deletions(-)

diff --git a/drivers/mmc/card/mmc_test.c b/drivers/mmc/card/mmc_test.c
-static int mmc_test_map_sg(struct mmc_test_mem *mem, unsigned long sz,
+static int mmc_test_map_sg(struct mmc_test_mem *mem, unsigned long size,

? ? ? ? ? ? ? ? ? ? ? ? ? struct scatterlist *sglist, int repeat,
? ? ? ? ? ? ? ? ? ? ? ? ? unsigned int max_segs, unsigned int max_seg_sz,
- ? ? ? ? ? ? ? ? ? ? ? ? ?unsigned int *sg_len)
+ ? ? ? ? ? ? ? ? ? ? ? ? ?unsigned int *sg_len, int min_sg_len)
?{
? ? ? ?struct scatterlist *sg = NULL;
? ? ? ?unsigned int i;
+ ? ? ? unsigned long sz = size;

? ? ? ?sg_init_table(sglist, max_segs);
+ ? ? ? if (min_sg_len > max_segs)
+ ? ? ? ? ? ? ? min_sg_len = max_segs;

? ? ? ?*sg_len = 0;
? ? ? ?do {
? ? ? ? ? ? ? ?for (i = 0; i < mem->cnt; i++) {
? ? ? ? ? ? ? ? ? ? ? ?unsigned long len = PAGE_SIZE << mem->arr[i].order;

+ ? ? ? ? ? ? ? ? ? ? ? if (min_sg_len && (size / min_sg_len < len))
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? len = size / min_sg_len;