From: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
To: "zack@owlfolio.org" <zack@owlfolio.org>,
"juntangc@amazon.com" <juntangc@amazon.com>
Cc: 'GNU C Library' <libc-alpha@sourceware.org>
Subject: bug fix for hp-timing.h (aarch64)
Date: Wed, 11 Jan 2023 22:49:08 +0000 [thread overview]
Message-ID: <PAWPR08MB8982320110E6CC2FF66F5F4E83FC9@PAWPR08MB8982.eurprd08.prod.outlook.com> (raw)
Hi Zack,
> - (Diff) = ((End) - (Start)) * (UINT64_C(1000000000) / freq); \
> + (Diff) = (((End) - (Start)) * UINT64_C(1000000000)) / freq; \
>
> This avoids using floating-point arithmetic but should still do the rescale correctly.
> (The multiplier and divisor are both guaranteed to be less than 2**32, so, as long
> as we do the multiplication in 64-bit arithmetic, we cannot lose bits via overflow.)
However this will overflow after about 16 seconds - and that's short even for basic
benchmarking. Since this code is not performance critical, using floating point here
is reasonable.
Cheers,
Wilco
next reply other threads:[~2023-01-11 22:49 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-11 22:49 Wilco Dijkstra [this message]
2023-01-12 14:38 ` Tang, Jun
2023-01-12 18:07 ` Wilco Dijkstra
2023-01-12 18:54 ` Zack Weinberg
2023-01-12 20:32 ` Wilco Dijkstra
2023-01-12 20:51 ` Noah Goldstein
2023-01-16 16:33 ` Wilco Dijkstra
2023-01-16 17:01 ` Noah Goldstein
2023-01-16 18:35 ` Wilco Dijkstra
2023-01-12 15:11 ` Zack Weinberg
-- strict thread matches above, loose matches on Subject: below --
2023-01-11 16:44 Tang, Jun
2023-01-11 17:22 ` Zack Weinberg
2023-01-31 14:47 ` Tang, Jun
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