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From: Cyril Hrubis <chrubis@suse.cz>
To: Li Wang <liwang@redhat.com>
Cc: Waiman Long <longman@redhat.com>,
	Eirik Fuller <efuller@redhat.com>, Waiman Long <llong@redhat.com>,
	ltp@lists.linux.it, Viresh Kumar <viresh.kumar@linaro.org>
Subject: Re: [LTP] [PATCH v2] clock_gettime04: set threshold based on the clock resolution
Date: Wed, 30 Mar 2022 11:49:00 +0200	[thread overview]
Message-ID: <YkQnjMOadd/hbRBI@yuki> (raw)
In-Reply-To: <CAEemH2eAaSyZiXE4G792U72iQvmOwQcVe+RoMMqjF7Bc0uajGQ@mail.gmail.com>

Hi!
> Thierically that's right, we only make the resolution as additional value
> to tolerate.
> 
> But I'm afraid this is the part we can not guarantee especially for VM.
> As from Eirik's test history, the KVM guest ever failed with "150ms" delay:
>   clock_gettime04.c:163: TFAIL: CLOCK_BOOTTIME(vDSO with old kernel spec):
> Difference between successive readings greater than 50 ms (2): 150

I do agree that on VMs all bets about timer precisions are off but I
still think that it makes more sense to run the test with greater deltas
there. As long as the VM has acces to high resolution timers we will
will have smaller delta for these clocks using them.

-- 
Cyril Hrubis
chrubis@suse.cz

-- 
Mailing list info: https://lists.linux.it/listinfo/ltp

  reply	other threads:[~2022-03-30  9:46 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-29  5:03 [LTP] [PATCH v2] clock_gettime04: set threshold based on the clock resolution Li Wang
2022-03-29 10:30 ` Cyril Hrubis
2022-03-29 21:04 ` Waiman Long
2022-03-30  3:16   ` Li Wang
2022-03-30  9:49     ` Cyril Hrubis [this message]
2022-03-30 16:13     ` Waiman Long
2022-03-31  3:01       ` Li Wang

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