From: Arnd Bergmann <arnd@xxxxxxxx> Subject: crc32: use ktime_get_ns() for measurement The crc32 test function measures the elapsed time in nanoseconds, but uses 'struct timespec' for that. We want to remove timespec from the kernel for y2038 compatibility, and ktime_get_ns() also helps make the code simpler here. It is also slightly better to use monontonic time, as we are only interested in the time difference. Link: http://lkml.kernel.org/r/20160617143932.3289626-1-arnd@xxxxxxxx Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Cc: "David S . Miller" <davem@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/crc32.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff -puN lib/crc32.c~crc32-use-ktime_get_ns-for-measurement lib/crc32.c --- a/lib/crc32.c~crc32-use-ktime_get_ns-for-measurement +++ a/lib/crc32.c @@ -979,7 +979,6 @@ static int __init crc32c_test(void) int i; int errors = 0; int bytes = 0; - struct timespec start, stop; u64 nsec; unsigned long flags; @@ -999,20 +998,17 @@ static int __init crc32c_test(void) local_irq_save(flags); local_irq_disable(); - getnstimeofday(&start); + nsec = ktime_get_ns(); for (i = 0; i < 100; i++) { if (test[i].crc32c_le != __crc32c_le(test[i].crc, test_buf + test[i].start, test[i].length)) errors++; } - getnstimeofday(&stop); + nsec = ktime_get_ns() - nsec; local_irq_restore(flags); local_irq_enable(); - nsec = stop.tv_nsec - start.tv_nsec + - 1000000000 * (stop.tv_sec - start.tv_sec); - pr_info("crc32c: CRC_LE_BITS = %d\n", CRC_LE_BITS); if (errors) @@ -1065,7 +1061,6 @@ static int __init crc32_test(void) int i; int errors = 0; int bytes = 0; - struct timespec start, stop; u64 nsec; unsigned long flags; @@ -1088,7 +1083,7 @@ static int __init crc32_test(void) local_irq_save(flags); local_irq_disable(); - getnstimeofday(&start); + nsec = ktime_get_ns(); for (i = 0; i < 100; i++) { if (test[i].crc_le != crc32_le(test[i].crc, test_buf + test[i].start, test[i].length)) @@ -1098,14 +1093,11 @@ static int __init crc32_test(void) test[i].start, test[i].length)) errors++; } - getnstimeofday(&stop); + nsec = ktime_get_ns() - nsec; local_irq_restore(flags); local_irq_enable(); - nsec = stop.tv_nsec - start.tv_nsec + - 1000000000 * (stop.tv_sec - start.tv_sec); - pr_info("crc32: CRC_LE_BITS = %d, CRC_BE BITS = %d\n", CRC_LE_BITS, CRC_BE_BITS); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
