From: Imre Kaloz <kaloz@kernel.org>
To: Stian Halseth <stian@itx.no>
Cc: davem@davemloft.net, Andreas Larsson <andreas@gaisler.com>,
Thomas Weissschuh <thomas.weissschuh@linutronix.de>,
Thomas Gleixner <tglx@kernel.org>,
sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sparc64: vdso: Flush the D-cache after updating the time data
Date: Sun, 27 Sep 2026 22:49:22 +0200 [thread overview]
Message-ID: <20260927204922.3783-1-kaloz@kernel.org> (raw)
In-Reply-To: <20260917082547.223729-1-stian@itx.no>
On Thu, 17 Sep 2026 10:25:47 +0200
Stian Halseth <stian@itx.no> wrote:
> On a Sun Fire V240 (UltraSPARC IIIi, clocksource stick) this makes
> clock_gettime(CLOCK_MONOTONIC) via the vDSO wrong for most calls on
> the tick CPU, by multiples of the 10 ms tick and up to a second, in
> about half of all processes: those that drew the other colour at
> exec.
Hi Stian,
Confirmed on a Sun Ultra 45 (UltraSPARC IIIi, SMP). The unpatched
kernel's vDSO clock_gettime() went stale on 3 out of 3 boots, up to
85% of CLOCK_MONOTONIC/CLOCK_REALTIME reads on the affected CPU, with
a lag up to 1492 ms. A kernel carrying this patch showed 0% stale
reads on 3 out of 3 boots.
Tested-by: Imre Kaloz <kaloz@kernel.org>
Best,
Imre
prev parent reply other threads:[~2026-09-27 20:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-17 8:25 Stian Halseth
2026-09-25 7:55 ` Thomas Weißschuh
2026-09-25 8:02 ` [PATCH v2] " Stian Halseth
2026-09-27 20:49 ` Imre Kaloz [this message]
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