Date: Fri, 29 May 2015 15:39:27 +0200 From: Sebastian Huber <sebastian.huber@embedded-brains.de> To: Poul-Henning Kamp <phk@phk.freebsd.dk> Cc: freebsd-hackers@freebsd.org Subject: Re: Problem with timecounters and memory model Message-ID: <55686C0F.9000101@embedded-brains.de> In-Reply-To: <85086.1432906578@critter.freebsd.dk> References: <55686300.3080100@embedded-brains.de> <85086.1432906578@critter.freebsd.dk>
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On 29/05/15 15:36, Poul-Henning Kamp wrote: > -------- > In message <55686300.3080100@embedded-brains.de>, Sebastian Huber write= s: > >> This version seems to work at least on uni-processor systems. Shouldn'= t >> there be real memory barriers the synchronize the reads/writes to >> th_generation for SMP machines? > yes, there should. > > (I must admit that I havn't looked at that code for about five or ten y= ears.) > Ok, what makes me wonder is why this problem didn't show up in FreeBSD.=20 In our case we observed backward jumps in the supposed to be monotonic=20 uptime. --=20 Sebastian Huber, embedded brains GmbH Address : Dornierstr. 4, D-82178 Puchheim, Germany Phone : +49 89 189 47 41-16 Fax : +49 89 189 47 41-09 E-Mail : sebastian.huber@embedded-brains.de PGP : Public key available on request. Diese Nachricht ist keine gesch=E4ftliche Mitteilung im Sinne des EHUG.
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