Very Computer

Hi !

I have a question about resident size of the process in Solaris.
There are two ways to get this value:

1. ps -o "pid rss"
   (will display it in the second column)

2. /usr/proc/bin/pmap -x $pid
   (will display it in the last line, second value)

problem:  this values noticeably differs.
question: What does it meen ??

Quote:> Hi !

> I have a question about resident size of the process in Solaris.
> There are two ways to get this value:

> 1. ps -o "pid rss"
>    (will display it in the second column)

> 2. /usr/proc/bin/pmap -x $pid
>    (will display it in the last line, second value)

> problem:  this values noticeably differs.
> question: What does it meen ??

In pmap, it is counted also from a shared segments, that is the part of
the memory, which is also reused by other pid's.

I think :)

That doesn't explain my simple test on Solaris 2.6 sun4u: "sleep 1000
&" has 704 kbytes rss from ps -o rss, but 824 kbytes of Resident and
744 Shared from pmap -x. 824-744=80 kbytes, way off from 704 kbytes.

If you look at the source code (free download), ps(1) uses
/proc/[pid]/psinfo while pmap(1) uses /proc/[pid]/xmap. I think
/proc/[pid]/psinfo is known to be a good source (/usr/ucb/ps uses this
structure too; David Curry's Systems Programming book also uses it if
I remember right). As to /proc/[pid]/xmap, I've found other problems.
For instance, when the process has a shared memory segment such as an
Oracle process, there could be a non-zero number under Private for the
shmid=?? segment in pmap -x output (Permissions shows shared
correctly). The Private number is either 0 or much smaller if intimate
shared memory is not used.

Yong Huang