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Date:   Mon, 28 Jun 2021 16:13:13 +0200
From:   Daniel Wagner <dwagner@suse.de>
To:     John Kacur <jkacur@redhat.com>
Cc:     Daniel Wagner <wagi@monom.org>, Mike Galbraith <efault@gmx.de>,
        RT <linux-rt-users@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Clark Williams <williams@redhat.com>,
        Johnathan Schwender <schwenderjonathan@gmail.com>,
        Peter Xu <peterx@redhat.com>
Subject: Re: [ANNOUNCE] rt-tests-2.0
Message-ID: <20210628141313.3fixpscbdc4ugnld@beryllium.lan>
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On Mon, Jun 28, 2021 at 09:50:25AM -0400, John Kacur wrote:
> > I'd say the tsbuf access is the one which triggers a pagefault.
> > 
> > John, I would suggest to move the rt_test_start() into rt_init() and
> > take the timestamp at the execution start (as my initial version was). I
> > think the additional pain in slightly more correct start timestamp
> > (which is also not defined what it actually means in this context) is
> > just not worth the effort.
> > 
> > Thanks,
> > Daniel
> > 
> 
> Send me a patch, and I'll have a look. The timerthread()function is
> sensitive anyway, so it's probably a good idea not to put that kind
> of thing there.
> 
> Note that the the code following the /* Get Current Time */
> is getting the time, but you probably want something rougher that
> you can call strftime on?

I think it's just the buffer strftime is writting into it. The page is
probably not mapped and hence the pagefault in the first access.

Anyway, I'll send a patch which moves the rt_test_start() into rt_init().