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SubjectRe: [PATCH] aoe: Use 64-bit timestamp in frame
Date
On Monday 11 May 2015 08:05:05 Tina Ruchandani wrote:
> 'struct frame' uses two variables to store the sent timestamp - 'struct
> timeval' and jiffies. jiffies is used to avoid discrepancies caused by
> updates to system time. 'struct timeval' uses 32-bit representation for
> seconds which will overflow in year 2038.
> This patch does the following:
> - Replace the use of 'struct timeval' and jiffies with ktime_t, which
> is a 64-bit timestamp and is year 2038 safe.
> - ktime_t provides both long range (like jiffies) and high resolution
> (like timeval). Using ktime_get (monotonic time) instead of wall-clock
> time prevents any discprepancies caused by updates to system time.
>
> Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>

Very nice!

> @@ -499,32 +497,15 @@ resend(struct aoedev *d, struct frame *f)
> static int
> tsince_hr(struct frame *f)
> {
> - struct timeval now;
> + ktime_t now;
> int n;
>
> - do_gettimeofday(&now);
> - n = now.tv_usec - f->sent.tv_usec;
> - n += (now.tv_sec - f->sent.tv_sec) * USEC_PER_SEC;
> + now = ktime_get();
> + n = ktime_to_us(ktime_sub(now, f->sent));
>

I would cut four extra lines by writing this as

return ktime_us_delta(ktime_get(), f->sent));

but the effect is exactly the same.

With that change, please add

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

Arnd


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