The shown speed is inversely proportional to the data size. See the output:
spi-nand: spi_nand nand@0: Micron SPI NAND was found. spi-nand: spi_nand nand@0: 256 MiB, block size: 128 KiB, page size: 2048, OOB size: 128 ... => mtd read.benchmark spi-nand0 $loadaddr 0 0x40000 Reading 262144 byte(s) (128 page(s)) at offset 0x00000000 Read speed: 63kiB/s => mtd read.benchmark spi-nand0 $loadaddr 0 0x20000 Reading 131072 byte(s) (64 page(s)) at offset 0x00000000 Read speed: 127kiB/s => mtd read.benchmark spi-nand0 $loadaddr 0 0x10000 Reading 65536 byte(s) (32 page(s)) at offset 0x00000000 Read speed: 254kiB/s In the spi-nand case 'io_op.len' is not always the same as 'len', thus we are using the wrong amount of data to derive the speed. Also make sure we are using 64-bit calculation to get a more precise results. Fixes: d246e70cf81d0 ("cmd: mtd: Enable speed benchmarking") Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevets...@iopsys.eu> Reviewed-by: Miquel Raynal <miquel.ray...@bootlin.com> --- cmd/mtd.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/cmd/mtd.c b/cmd/mtd.c index cee3a7e43ef..d4e1f83b91c 100644 --- a/cmd/mtd.c +++ b/cmd/mtd.c @@ -469,7 +469,7 @@ static int do_mtd_io(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]) { bool dump, read, raw, woob, benchmark, write_empty_pages, has_pages = false; - u64 start_off, off, len, remaining, default_len; + u64 start_off, off, len, remaining, default_len, speed; unsigned long bench_start, bench_end; struct mtd_oob_ops io_op = {}; uint user_addr = 0, npages; @@ -595,9 +595,10 @@ static int do_mtd_io(struct cmd_tbl *cmdtp, int flag, int argc, if (benchmark && bench_start) { bench_end = timer_get_us(); + speed = (len * 1000000) / (bench_end - bench_start); printf("%s speed: %lukiB/s\n", read ? "Read" : "Write", - ((io_op.len * 1000000) / (bench_end - bench_start)) / 1024); + (unsigned long)(speed / 1024)); } led_activity_off(); -- 2.50.1