Re: subsystem_debug and mem_used in proc

On Apr 04, 2007  11:28 -0800, Jan H. Julian wrote:
> Could someone please clarify the use of the proc values for 
> subsystem_debug and memused.  In regard to 
> /proc/sys/portals/subsystem_debug and /proc/sys/portals/debug, should 
> both be set to zero to totally turn of debugging?
> 
> In regard to /proc/sys/lustre/memused we see quite a variety of 
> entries included many with negative values.  Does the negative value 
> have a particular meaning?
> For instance "cat /proc/sys/lustre/memused" for 9 nodes shows:
> ...
> mg07  102186899
> mg08  101775995
> mg09  -1323553489
> mg10  -1328553965
> mg11  -1378379739
> mg12  -1347059989
> mg13  -1364717487
> mg14  -1358477913
> mg15  24680370
>
> These are 16 core  machines with 64GB of resident memory.

This appears to be an overflow of a 32-bit counter.  It isn't strictly
harmful, because it will underflow an equal amount later on and should
return to zero when Lustre unmounts.  It does make this stat less useful
on machines with lots of RAM.

Are these client or server nodes?  I'm a bit surprised that Lustre would
be allocating > 2GB of RAM.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.