Thursday, March 31, 2011

Solaris Online forum

A rare opportunity is coming April 14, Oracle is sharing information on their Solaris strategy and upcoming Solaris 11 features.

The agenda taken from the registration site:

"9:00 a.m. - 9:45 a.m. PT
Oracle Solaris Strategy Overview
Bill Nesheim, VP Oracle Solaris Engineering

9:45 a.m. - 10:00 a.m. PT
An Industry Analyst's View of the Operating System Market
Gary Chen, IDC

10:00 a.m. - 10:45 a.m. PT
Manage Your Deployments With Image Packaging System and the Automated Installer
Bart Smaalders, Oracle Solaris Engineering
Dave Miner, Oracle Solaris Engineering
Glynn Foster, Oracle Solaris Product Management
Isaac Rozenfeld, Oracle Solaris Product Management

10:45 a.m. - 11:30 a.m. PT
Get More out of Your Oracle Solaris Environments With Virtualization
Dan Price, Oracle Solaris Engineering
Nicolas Droux, Oracle Solaris Engineering
Duncan Hardie, Oracle Solaris Product Management

11:30 a.m. - 12:15 p.m. PT
Learn How All New Features in Oracle Solaris 11 Raise The Bar For Operating Systems
Markus Flierl, Sr. Director Oracle Solaris Engineering
Liane Praza, Oracle Solaris Engineering
Joost Pronk, Oracle Solaris Product Management

Register and get more information here.

Tuesday, March 15, 2011

Sort memory capping out

I had a curios problem today, on a otherwise lightly loaded machine with plenty of memory left login as the Oracle user took tens of seconds to complete. Since it was the souring of a shell script that was stalling identify where the time was spent:

$ set -x
$ . /path/to/oraenv
+ nawk { print $2 }
+ sort

The whole delay was spent in sort(1) for no obvious reason. Truss shows the system call:
24.8167 sysconfig(_CONFIG_AVPHYS_PAGES) = 1500736
0.0011 sysconfig(_CONFIG_PAGESIZE) = 8192
0.0008 getpid() = 24178 [24177]

It took 24 seconds to get the number of available memory pages, a operation that worked fine in the global zone. The sysconfig source shows us that the call is very different for a global zone and for a memory capped zone:

if (!INGLOBALZONE(curproc) &&
curproc->p_zone->zone_phys_mcap != 0) {
pgcnt_t cap, rss, free;
vmusage_t in_use;
size_t cnt = 1;

cap = btop(curproc->p_zone->zone_phys_mcap);
if (cap > physinstalled)
return (freemem);

if (vm_getusage(VMUSAGE_ZONE, 1, &in_use, &cnt,
FKIOCTL) != 0)

If there is a physical memory capping set for the zone that is less than the amount of physical memory in the machine vm_getusage will be called, it will in turn look at every memory segment for every process , this can take quite a while on larger if the zone is a heavy allocator of memory, in this case the zone was using about 50GB of memory. This is not something you want to do every time a shell script calls $(sort). If you have ever used prstat -Z with large local zones you have seen the effects of this, it can take a long time.

Comment from the source:
"This file implements the getvmusage() private system call.
getvmusage() counts the amount of resident memory pages and swap
reserved by the specified process collective. A "process collective" is
the set of processes owned by a particular, zone, project, task, or user."

The source of the problem in sort was in utility.c:
size_t phys_total = sysconf(_SC_PHYS_PAGES) * sysconf(_SC_PAGESIZE);
It seems like no other utilities in solaris uses sysconf(_SCPHYS_PAGES) which is why we had no other problems.

The short time solution was to disable the physical memory cap for these zones:
# rcapadm -z zone01 -m 0