How to test memory after memory upgrade? I recently upgraded my macbook from 4G to 8G and wonder if there's a tool to test the quality of new memory.
I found memtest 4.22 seems only test about 1G:

$ memtest all 2

Memtest version 4.22 (64-bit)
Copyright (C) 2004 Charles Cazabon
Copyright (C) 2004-2008 Tony Scaminaci (Macintosh port)
Licensed under the GNU General Public License version 2 only

Mac OS X 10.9 (13A603) running in multiuser mode
Memory Page Size: 4096
System has 4 Intel core(s) with SSE
Requested memory: 1048MB (1099390976 bytes)
Available memory: 1048MB (1099390976 bytes)
Allocated memory: 1048MB (1099390976 bytes) at local address 0x0000000101000000
Attempting memory lock... locked successfully
Partitioning memory into 2 comparison buffers...
Buffer A: 524MB (549695488 bytes) starts at local address 0x0000000101000000
Buffer B: 524MB (549695488 bytes) starts at local address 0x0000000121c3b000


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UPDATE:

I reboot into single user mode as described in this question, and test again. Works better, about 7G memory tested. So I guess the missing 1G is reserved for the graphics card?
I suggest you to install memtester for example with MacPorts:

$ port install memtester


and use it:

$ memtester 2G
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 2048MB (2147483648 bytes)
got  2048MB (2147483648 bytes), trying mlock ...locked.
Loop 1:
  Stuck Address       : ok         
  Random Value        : ok
  Compare XOR         : ok
  Compare SUB         : ok
  Compare MUL         : ok
  Compare DIV         : ok
  Compare OR          : ok
  Compare AND         : ok
  Sequential Increment: ok
[...]