On Sunday 31 January 2016 22:43:08 Abhilash Jindal wrote:
> Wall time obtained from getnstimeofday gives 32 bit timeval which can only
> represent time until January 2038. This patch moves to ktime_t, a 64-bit time.
>
> Also, wall time is susceptible to sudden jumps due to user setting the time or
> due to NTP. Boot time is constantly increasing time better suited for
> subtracting two timestamps.
>
> Signed-off-by: Abhilash Jindal <klock.android@xxxxxxxxx>
Everything looks correct to me, nice work!
I have a few comments to make the approach consistent with what we have
been doing with other drivers:
Using boottime sounds like a correct approach, but I wonder whether
we should just use monotonic time instead, as we do for most conversions.
> static void mmc_test_print_avg_rate(struct mmc_test_card *test, uint64_t bytes,
> - unsigned int count, struct timespec *ts1,
> - struct timespec *ts2)
> + unsigned int count, ktime_t tm1,
> + ktime_t tm2)
> {
> unsigned int rate, iops, sectors = bytes >> 9;
> uint64_t tot = bytes * count;
> - struct timespec ts;
> -
> - ts = timespec_sub(*ts2, *ts1);
> + ktime_t tm = ktime_sub(tm2, tm1);
> + struct timespec ts = ktime_to_timespec(tm);
Please use timespec64 here, otherwise we have to come back to the driver
again to change that when we remove 'struct timespec'.
> - rate = mmc_test_rate(tot, &ts);
> - iops = mmc_test_rate(count * 100, &ts); /* I/O ops per sec x 100 */
> + rate = mmc_test_rate(tot, tm);
> + iops = mmc_test_rate(count * 100, tm); /* I/O ops per sec x 100 */
>
> pr_info("%s: Transfer of %u x %u sectors (%u x %u%s KiB) took "
> "%lu.%09lu seconds (%u kB/s, %u KiB/s, "
When you do that, please be aware that you have to use a type cast here
and print the tv_sec portion using either %lu or %llu, with the matching
cast: 64-bit systems use 'long tv_sec' and 32-bit systems use 'long long
tv_sec' here for obscure reasons.
> @@ -1854,7 +1848,8 @@ static int mmc_test_rnd_perf(struct mmc_test_card *test, int write, int print,
> {
> unsigned int dev_addr, cnt, rnd_addr, range1, range2, last_ea = 0, ea;
> unsigned int ssz;
> - struct timespec ts1, ts2, ts;
> + ktime_t tm1, tm2, tm;
> + struct timespec ts;
> int ret;
>
> ssz = sz >> 9;
Same here.
> @@ -1863,10 +1858,11 @@ static int mmc_test_rnd_perf(struct mmc_test_card *test, int write, int print,
> range1 = rnd_addr / test->card->pref_erase;
> range2 = range1 / ssz;
>
> - getnstimeofday(&ts1);
> + tm1 = ktime_get_boottime();
> for (cnt = 0; cnt < UINT_MAX; cnt++) {
> - getnstimeofday(&ts2);
> - ts = timespec_sub(ts2, ts1);
> + tm2 = ktime_get_boottime();
> + tm = ktime_sub(tm2, tm1);
> + ts = ktime_to_timespec(tm);
> if (ts.tv_sec >= 10)
Alternatively, you could do
if (ktime_to_ns(tm) >= 10 * NSEC_PER_SEC)
Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
