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Date:   Tue, 10 Jan 2023 13:29:21 -0800
From:   "Paul E. McKenney" <paulmck@kernel.org>
To:     Willy Tarreau <w@1wt.eu>
Cc:     linux-kernel@vger.kernel.org, Sven Schnelle <svens@linux.ibm.com>
Subject: Re: [PATCH 0/4] nolibc: add support for the s390 platform
Message-ID: <20230110212921.GR4028633@paulmck-ThinkPad-P17-Gen-1>
Reply-To: paulmck@kernel.org
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On Tue, Jan 10, 2023 at 06:53:47PM +0100, Willy Tarreau wrote:
> On Tue, Jan 10, 2023 at 08:32:10AM -0800, Paul E. McKenney wrote:
> > On Tue, Jan 10, 2023 at 05:12:49PM +0100, Willy Tarreau wrote:
> > > On Tue, Jan 10, 2023 at 06:53:34AM -0800, Paul E. McKenney wrote:
> > > > Here is one of them, based on both the fixes and Sven's s390 support.
> > > > Please let me know if you need any other combination.
> > > 
> > > Thanks, here's the problem:
> > > 
> > > > 0 getpid = 1                             [OK]
> > > > 1 getppid = 0                            [OK]
> > > > 3 gettid = 1                             [OK]
> > > > 5 getpgid_self = 0                       [OK]
> > > > 6 getpgid_bad = -1 ESRCH                 [OK]
> > > > 7 kill_0[    1.940442] tsc: Refined TSC clocksource calibration: 2399.981 MHz
> > > > [    1.942334] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x229825a5278, max_idle_ns: 440795306804 ns
> > > >  = 0                             [OK]
> > > > 8 kill_CONT = 0           [    1.944987] clocksource: Switched to clocksource tsc
> > > >                [OK]
> > > > 9 kill_BADPID = -1 ESRCH                 [OK]
> > > (...)
> > > 
> > > It's clear that "grep -c ^[0-9].*OK" will not count all of them (2 are
> > > indeed missing).
> > > 
> > > We could probably start with "quiet" but that would be against the
> > > principle of using this to troubleshoot issues. I think we just stick
> > > to the current search of "FAIL" and that as long as a success is
> > > reported and the number of successes is within the expected range
> > > that could be OK. At least I guess :-/
> > 
> > Huh.  Would it make sense to delay the start of the nolibc testing by a
> > few seconds in order to avoid this sort of thing?  Or would that cause
> > other problems?
> 
> That would be quite annoying. Delaying is never long enough for some
> issues, too long for the majority of cases where there is no issue. I'd
> suggest that we just rely on the fail count for now (as it is) and that
> will allow us to collect a larger variety of discrepancies and probably
> figure a better solution at some point. For example if we find that it's
> always the TSC that does this, maybe starting x86 with notsc will be a
> good fix.

Sounds good to me!

							Thanx, Paul