We found h_vmem to be highly unpredictable, especially with java-based
applications. Stack settings were screwed up, certain applications
wouldn't launch (segfaults), and hard limits were hard to determine for
things like MPI applications. When your master has to launch 1024 MPI
sub-tasks (qrsh), it generally eats up more VMEM than the slave tasks
do. It was just hard to get right.
-Brian
Brian Smith
Sr. System Administrator
Research Computing, University of South Florida
4202 E. Fowler Ave. SVC4010
Office Phone: +1 813 974-1467
Organization URL: http://rc.usf.edu
On 08/29/2012 11:33 AM, Reuti wrote:
Am 29.08.2012 um 17:21 schrieb Brian Smith:
We use mem_free variable as a consumable. Then, we use a cronjob called
memkiller that terminates jobs if they go over their requested (or default)
memory allocation and
It would be more straight forward to use directly h_vmem. This is controlled by
SGE and the job exceeding the limit will be killed by SGE. If you consume it as
a consumable on a exechost level, it could be set to the built in physical
memory.
Was there any reason to use mem_free?
-- Reuti
1. Swap space on node is used
2. Swap rate is greater than 100 I/Os per second
The user gets emailed with a report if this happens.
This has made dealing with the oom killer a thing of the past in our shop.
We manage memory on the principle that swap should NEVER be used. If you're
hitting oom killer, you're pretty far beyond that in terms of memory
utilization; if performance is a consideration, MHO is you should be looking to
schedule your memory usage accordingly. Oom killer shouldn't be a factor if
memory is handled as a scheduler consideration.
-Brian
Brian Smith
Sr. System Administrator
Research Computing, University of South Florida
4202 E. Fowler Ave. SVC4010
Office Phone: +1 813 974-1467
Organization URL: http://rc.usf.edu
On 08/29/2012 11:02 AM, Ben De Luca wrote:
I was wondering, how people deal with oom conditions on there cluster.
We constantly have machines that die because the oom killer takes out
critical system services.
Has any experiance with the oom_adj proc value, or a patch to grid to
support it?
/proc/[pid]/oom_adj (since Linux 2.6.11)
This file can be used to adjust the score used to select
which process
should be killed in an out-of-memory (OOM) situation.
The kernel uses
this value for a bit-shift operation of the process's
oom_score value:
valid values are in the range -16 to +15, plus the
special value -17,
which disables OOM-killing altogether for this process.
A positive
score increases the likelihood of this process being
killed by the OOM-
killer; a negative score decreases the likelihood. The
default value
for this file is 0; a new process inherits its parent's oom_adj
setting. A process must be privileged
(CAP_SYS_RESOURCE) to update
this file.
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