Very Computer

What is the meaning of RSS(Resident Set Size) of the output of ps
and prstat?

RCLM

Quote:> What is the meaning of RSS(Resident Set Size) of the output of ps
> and prstat?

It's the amount of RAM actually used by the process - as opposed
to that which has been paged (swapped) out.  For example, a 10 MB
process might have an RSS of 8 MB; this means that 8 MB of the
process' virtual memory is in RAM, and the other 2 MB is paged
out to disk.

--
Rich Teer

President,
Rite Online Inc.

Voice: +1 (250) 979-1638
URL: http://www.rite-online.net

Any way to limit the max RSS (quota) on a per process basis,
without limiting the process's size (swap usage)?  If sometimes
allowed to accumulate a lot of RAM, transfer back to the higher
priority processes (user's desktop session) when they need it is
too slow.

Like a "limit resident" instead of "limit datasize"?

You could do that with any SunOS release prior to SunOS-4.0 using
limit memoryuse.

On 4.0 this was still present but non-functional.

The reason is that Sun introduced a new orthogonal memory management concept
with SnOS-4.0 and this did not allow to find an 'owner' for a page from
the page info (that is used by the pager daemon).

In 1988 I hacked the scheduler for SunOS-4.0 and found a way to make it work
agin. It was a simple hack. If the scheduler checked a process to decide whether
it should be the next to run, I compared the RSS size with the limit.
If the process was using more than the limit I called swapout() and thus the
process was less 'nice' than other processes. This worked like a charm
for background processes!

Unfortunately, Sun decided to remove the apropriate resource limit with
Solaris 2 aka SunOS-5.x

--



URL:  http://www.fokus.gmd.de/usr/schilling    ftp://ftp.fokus.gmd.de/pub/unix

Quote:> Any way to limit the max RSS (quota) on a per process basis,
> without limiting the process's size (swap usage)?  If sometimes

AFAIK, no, there isn't.

Quote:> allowed to accumulate a lot of RAM, transfer back to the higher
> priority processes (user's desktop session) when they need it is
> too slow.

IF they're higher priority, they'll be running more often anyay.
Depending on what OS your using, priority paging might help you
out in this situation.

Quote:> Like a "limit resident" instead of "limit datasize"?

If priority paging doesn't do the trick, I can only think of one
more idea: buy more RAM.

--
Rich Teer

President,
Rite Online Inc.

Voice: +1 (250) 979-1638
URL: http://www.rite-online.net

|Any way to limit the max RSS (quota) on a per process basis,
|without limiting the process's size (swap usage)?

To understand why this would be difficult and not very useful, remember
that RSS includes pages of shared objects loaded into the process,
so a processes RSS can increase because a completely unrelated process
loaded in one of the pages in the shared object they both have loaded.

On the other hand, it sounds like what you are looking for is greater
control over how resources are allocated between processes, which is
available via the Solstice Resource Manager product:
        http://www.sun.com/software/resourcemgr/

--
________________________________________________________________________


  Working for, but definitely not speaking for, Sun Microsystems, Inc.

Sounds livable, unless I haven't got the point.  User can pad their quota
settings for it.  The process would start slowly paging out at that time
to get back under quota (the intention) instead of later when memory got
really short (when it's too late to preserve near-zero-impact to the
desktop experience).  If using "limit datasize" to restrict a process's
worst case swap impact, are you similarly not quite fairly counting
shared libs?

Stabbing at an improvement:  Apply the quota instead to a new count,
AccessedSetSize, and defer counting each loaded shared object page towards
any process's "ASS" until they access it first time. ;)

Quote:> On the other hand, it sounds like what you are looking for is greater
> control over how resources are allocated between processes, which is
> available via the Solstice Resource Manager product:
>    http://www.sun.com/software/resourcemgr/

I'll check it out.  Thanks for the encouraging responses.  Nice to
hear it was once.  How did SUNOS-before-4 handle it for shared libs?