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Date:      Sun, 26 Apr 2015 15:05:03 -0500 (CDT)
From:      "Valeri Galtsev" <galtsev@kicp.uchicago.edu>
To:        Fernando =?iso-8859-1?Q?Apestegu=C3=ADa?= <fernando.apesteguia@gmail.com>
Cc:        "User Questions" <freebsd-questions@freebsd.org>
Subject:   Re: Debugging bad memory problems
Message-ID:  <5480.69.209.235.143.1430078703.squirrel@cosmo.uchicago.edu>
In-Reply-To: <CAGwOe2Y+RuT7MuCTBq_swn-Ny-BS-WH1J=bZTbE9L4tuv8LmCA@mail.gmail.com>
References:  <CAGwOe2Y+RuT7MuCTBq_swn-Ny-BS-WH1J=bZTbE9L4tuv8LmCA@mail.gmail.com>

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On Sun, April 26, 2015 12:11 pm, Fernando ApesteguĂ­a wrote:
> Hi,
>
> I suspect my old and beloved AMD64 laptop is suffering from bad memory
> problems: I get random crashes of well tested programs like sh, which,
> etc even when I executed some of them from /rescue.

If RAM is a suspect the first thing I would do is re-seat memory modules.
Open the box. (Observe static precautions!) Remove memory modules. Install
them again.

Do memtest86 (by booting into memtest86, you can have that in your boot
options, or you can boot off external media as others suggested).

If you still have problems: try to run with one memory module instead of
two. At some point when they went to higher RAM speeds memory bus
amplifier became more fragile (some chips, some manufacturers, as not it
is part of CPU, this may be true only about some of the CPU models). You
sometimes can slightly fry it if you merely leave laptop running on
battery, letting battery run down and laptop powering off due to that.
With some of chips this may lead to slightly frying it - memory controller
portion of it, address bus amplifier in particular. Bus amplifier becomes
slightly lower frequency, which results in poorer handling capacitive load
(which is larger if you have more RAM), and it is marginally OK,
occasionally having address errors. Going to one module may resolve this.
You will know if this is likely the case if memtest86 is successful with
each of single RAM modules, but fails (in random places, often not
reproducible) with both.

Good luck!

Valeri

>
> I wanted to check the memory banks. I installed
> /usr/ports/sysutils/memtest86+ and try to run it at boot. According to
> the documentation, from the boot loader prompt:
>
> unload
> load /boot/opt/memtest86+
> boot
>
> But at the time of loading the file, the laptop reboots.
>
> I also tried /usr/ports/sysutils/memtest. But when I run it (as root), I
> get:
>
> $memtester 1G
>
> memtester version 4.3.0 (64-bit)
> Copyright (C) 2001-2012 Charles Cazabon.
> Licensed under the GNU General Public License version 2 (only).
>
> pagesize is 4096
> pagesizemask is 0xfffffffffffff000
> want 1024MB (1073741824 bytes)
> got  1024MB (1073741824 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073737728 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073733632 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073729536 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073725440 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073721344 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073717248 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073713152 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073709056 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073704960 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073700864 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073696768 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073692672 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073688576 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073684480 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073680384 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073676288 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073672192 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073668096 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073664000 bytes), trying mlock ...too many pages,
> reducing...
> got  1023MB (1073659904 bytes), trying mlock ...too many pages,
> reducing...
>
> ...
> ...
>
> got  0MB (73728 bytes), trying mlock ...too many pages, reducing...
> got  0MB (69632 bytes), trying mlock ...too many pages, reducing...
> got  0MB (65536 bytes), trying mlock ...locked.
>
> Any help with these two problems or any alternative programs?
>
> Thanks in advance.
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++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
++++++++++++++++++++++++++++++++++++++++



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