Date: Fri, 01 Mar 2019 14:11:33 -0700 From: Ian Lepore <ian@freebsd.org> To: Poul-Henning Kamp <phk@phk.freebsd.dk>, Mark Millard <marklmi@yahoo.com>, Mark Millard via freebsd-hackers <freebsd-hackers@freebsd.org> Cc: Konstantin Belousov <kib@freebsd.org>, bde@freebsd.org, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org> Subject: Re: powerpc64 head -r344018 stuck sleeping problems: th->th_scale * tc_delta(th) overflows unsigned 64 bits sometimes [patched failed] Message-ID: <210dfd0f50ee6b1149c914ee503502654eb5f328.camel@freebsd.org> In-Reply-To: <6669.1551473821@critter.freebsd.dk> References: <D3D7E9F4-9A5E-4320-B3C8-EC5CEF4A2764@yahoo.com> <20190228145542.GT2420@kib.kiev.ua> <20190228150811.GU2420@kib.kiev.ua> <962D78C3-65BE-40C1-BB50-A0088223C17B@yahoo.com> <28C2BB0A-3DAA-4D18-A317-49A8DD52778F@yahoo.com> <20190301112717.GW2420@kib.kiev.ua> <679402FF-907C-43AF-B18C-8C9CC857D7A6@yahoo.com> <6669.1551473821@critter.freebsd.dk>
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On Fri, 2019-03-01 at 20:57 +0000, Poul-Henning Kamp wrote: > -------- > In message <679402FF-907C-43AF-B18C-8C9CC857D7A6@yahoo.com>, Mark > Millard via freebsd-hackers writes: > > > > I must admit that 2 seconds of interval where the timehands where > > > not updated is too much. > > I have no idea how you got in that situation, but it is very far > from how timecounters were designed to work. > I wonder if it's fallout from reducing the number of timehands to 2, which always struck me as a really bad idea. I know of at least one arm configuration which fails because of it (it takes a combo of a single- core system, and a pps capture driver that uses hardware latching of the timer and the polling method for reading the latched value; given all that, at least 4 sets of timehands are needed to avoid losing PPS events due to generation changes). -- Ian
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