From: Miroslav Lichvar <mlichvar@redhat.com>
To: Joerg Vehlow <lkml@jv-coder.de>
Cc: Greg KH <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
John Stultz <john.stultz@linaro.org>
Subject: Re: [4.14] Failing selftest timer/adjtick
Date: Thu, 11 Feb 2021 11:59:44 +0100 [thread overview]
Message-ID: <20210211105944.GG1903164@localhost> (raw)
In-Reply-To: <897e03f9-4062-d34f-0445-ff4f047ccd13@jv-coder.de>
On Thu, Feb 11, 2021 at 11:33:05AM +0100, Joerg Vehlow wrote:
> > My suggestion for a fix would be to increase the limit in the failing
> > test.
> Thanks, that's what I expected. But I still wonder why the test is failing
> almost 100% of time for me on qemu-arm64 (running on x86). Is this a
> regression in 4.14, that was working at some point or was it never tested on
> arm?
I don't think it is specific to arm or that it is a regression. I
think the virtual machine just happens to be too idle for the test.
There may be unrelated changes, maybe in the kernel, qemu, or
applications, that caused the rate of the clock updates to decrease so
much that the instability now triggers the failure in the test. The
issue with the clock was there since NO_HZ was introduced, but it
becomes more severe as the activity of the kernel decreases.
--
Miroslav Lichvar
next prev parent reply other threads:[~2021-02-11 11:06 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-10 12:43 [4.14] Failing selftest timer/adjtick Joerg Vehlow
2021-02-10 13:00 ` Greg KH
2021-02-10 13:07 ` Joerg Vehlow
2021-02-10 13:19 ` Miroslav Lichvar
2021-02-10 18:59 ` Naresh Kamboju
2021-02-11 10:34 ` Joerg Vehlow
2021-02-11 10:33 ` Joerg Vehlow
2021-02-11 10:45 ` Greg KH
2021-02-11 10:59 ` Miroslav Lichvar [this message]
2021-02-18 7:05 ` Joerg Vehlow
2021-03-01 7:04 ` Joerg Vehlow
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