Date: Wed, 23 Mar 2011 16:42:31 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-arch@freebsd.org Subject: Re: kernel memory checks on boot vs. boot time Message-ID: <imd4d7$dbc$1@dough.gmane.org> In-Reply-To: <4D89DEB9.7060509@freebsd.org> References: <alpine.BSF.2.00.1103221634241.6104@ai.fobar.qr> <201103221551.14289.jhb@freebsd.org> <4D88FE89.1060900@feral.com> <4D89DEB9.7060509@freebsd.org>
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On 23/03/2011 12:51, Andriy Gapon wrote: > on 22/03/2011 21:54 Matthew Jacob said the following: >> John Baldwin wrote: >>> >>> Do other platforms bother with these sorts of memory tests? If not I'd vote >>> to just drop it. I think this mattered more when you didn't have things like >>> SMAP (so you had to guess at where memory ended sometimes). Also, modern >>> server class x86 machines generally support ECC RAM which will trigger a >>> machine check if there is a problem. I doubt that the early checks are >>> catching anything even for the non-ECC case. >>> >>> If nothing else, I would definitely drop this from amd64 (all those systems >>> have SMAP and machine check support, etc.). >>> >>> >> Memory checks are definitely still useful. Loading the linux mem tester has >> helped find lots of problems, even on so-called modern machines. I'd voter for >> leaving this as an option. > > I think that you talk about a different kind of memory checking/testing. > What we have in FreeBSD looks a lot like what BIOSes use(d) to do on startup. > Besides, AFAIR, it doesn't report any results to you. I'd say that is the main point. At least once I've thought the machine hung when it was doing this check for a surprisingly long time. I'd vote for *at least* adding a "twirling baton" indicator (every 1 GB or so) that something is going on, on all platforms :) If these tests have any effect at all (how can they fail? has anyone seen them fail?) I'd vote to keep them enabled by default, with a tunable to optionally disable them, as every little bit helps for reliability. If there is no effect at all from the tests, then just remove them.home | help
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