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Date:   Wed, 17 Aug 2022 12:21:03 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Sergei Trofimovich <slyich@gmail.com>
Cc:     linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org
Subject: Re: [PATCH] ia64: fix clock_getre(CLOCK_MONOTONIC) to report ITC
 frequency
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In-Reply-To: <20220815054944.4130786-1-slyich@gmail.com>
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On Mon, 15 Aug 2022 06:49:44 +0100 Sergei Trofimovich <slyich@gmail.com> wr=
ote:

> clock_gettime(CLOCK_MONOTONIC, &tp) is very precise on ia64 as it uses
> ITC (similar to rdtsc on x86). It's not quite a hrtimer as it is a few
> times slower than 1ns. Usually 2-3ns.
>=20
> clock_getres(CLOCK_MONOTONIC, &res) never reflected that fact and
> reported 0.04s precision (1/HZ value).
>=20
> In https://bugs.gentoo.org/596382 gstreamer's test suite failed loudly
> when it noticed precision discrepancy.
>=20
> Before the change:
>=20
>     clock_getres(CLOCK_MONOTONIC, &res) reported 250Hz precision.
>=20
> After the change:
>=20
>     clock_getres(CLOCK_MONOTONIC, &res) reports ITC (400Mhz) precision.
>=20
> The patch is based on matoro's fix. It adds a bit of explanation why we
> need to special-case arch-specific clock_getres().
>=20

It would be best (and nice) to include the original developer's
Signed-off-by: and to Cc =C9meric Maschino if possible?

Could you please take care of these paperwork issues?