topic Re: How to get dynamic memory information from another running process? in Operating System - OpenVMS

How to get dynamic memory information from another running process?

Davor_7 — Sun, 22 Jan 2006 21:32:09 GMT

i know the running process's id/name.
my login account has the all privilege.

i want to know the dynamic memory usage for this running process after my account login.
how can i do that?

Re: How to get dynamic memory information from another running process?

Karl Rohwedder — Mon, 23 Jan 2006 00:51:08 GMT

Have you looked at the lexical function F$GETJPI(PID,ITEM)?
It allows to gather much info from processes including e.g. the varias working set sizes, virtualpagecount ...

regards Kalle

Re: How to get dynamic memory information from another running process?

Davor_7 — Mon, 23 Jan 2006 01:12:26 GMT

yes.
now i have known how to get the physical memory usage of a process.
but how to know a dynamic memory usage ?
no idea...

Re: How to get dynamic memory information from another running process?

David B Sneddon — Mon, 23 Jan 2006 01:20:11 GMT

Davor,

Can you explain exactly what _YOU_ mean by
"dynamic memory information"?

Dave

Re: How to get dynamic memory information from another running process?

Davor_7 — Mon, 23 Jan 2006 01:33:17 GMT

i mean how many dynamic memory the running process uses.
for your own process, you can type $sho proc/mem to show the PDMA. but how to know the value from another process which you donot own?

also, is there any value-related between dynamic memory and physical memory?
the physical memory i calculated is far more then the dynamic memory...

Re: How to get dynamic memory information from another running process?

David B Sneddon — Mon, 23 Jan 2006 01:40:21 GMT

What problem are you trying to solve?

Re: How to get dynamic memory information from another running process?

Davor_7 — Mon, 23 Jan 2006 02:02:36 GMT

i use this command to get the physical memory utilizaion and calculate all the independant process
$ mem=F$GETJPI(pid,"PPGCNT")+F$GETJPI(pid,"GPGCNT")
as HP says, the result for this command is a unit of "page", you know 1 page = 8KB in alpha
so, i summarize the whole result but see it's >100G. the physical memory in my node is just <10G... how come?
this is my problem...

Re: How to get dynamic memory information from another running process?

Volker Halle — Mon, 23 Jan 2006 02:22:38 GMT

Davor,

PPGCNT (process private pages) and GPGCNT (process global pages) are measured in PAGELETS = 512 bytes, the size of the old VAX page.

Global pages are also shared between multiple processes and a global page mapped by multiple processes only exists ONCE in physical memory, so you can't add those numbers.

The term 'dynamic memory' actually refers to the Process Dynamic Memory Area shown by SHOW PROC/MEMORY, which is a process-private pool of memory in P1 space.

Volker.

Re: How to get dynamic memory information from another running process?

David B Sneddon — Mon, 23 Jan 2006 02:26:48 GMT

Firstly, the counts returned in PPGCNT and GPGCNT
do not necessarily reflect physical memory usage.
Secondly, by counting the GPGCNT for every process,
you are ignoring the fact that the global pages are
likely to be shared... and should therefore NOT
be counted multiple times.
You also need to take into account that pages are
not necessarily in memory but may be in a pagefile
or other disk file (images).

Re: How to get dynamic memory information from another running process?

Davor_7 — Mon, 23 Jan 2006 02:28:19 GMT

you mentioned that:
PPGCNT (process private pages) and GPGCNT (process global pages) are measured in PAGELETS = 512 bytes, the size of the old VAX page.

but from HP.
it says that it's the "page" unit
pls refer to:
For a given process with PID in the symbol "pid", the total number of pages
currently in the working set is:

$ mem=F$GETJPI(pid,"PPGCNT")+F$GETJPI(pid,"GPGCNT")

Re: How to get dynamic memory information from another running process?

Davor_7 — Mon, 23 Jan 2006 02:30:01 GMT

To david & Halle

yes. global pages are shared.
but even if i only calculate with the private pages. it's also very huge...

Re: How to get dynamic memory information from another running process?

David B Sneddon — Mon, 23 Jan 2006 02:32:45 GMT

Yes the number may be huge, but you are ignoring
the fact that pages in the working set may not
be physically in memory.

Re: How to get dynamic memory information from another running process?

Volker Halle — Mon, 23 Jan 2006 02:34:18 GMT

Davor,

please have a look in the System Services Manual for explanation of the arguments to the $GETJPI system service:

JPI$_PPGCNT
Returns the number of pages (on VAX systems) or pagelets (on Alpha and I64 systems) the process has in the working set. This is a longword integer value.

These are the process-private pagelets in the process working set, so they WILL be in physical memory at that time.

Volker.

Re: How to get dynamic memory information from another running process?

Davor_7 — Mon, 23 Jan 2006 02:41:26 GMT

To Halle
all right, now we have 2 versions for the PPGCNT output, hehe. manual says it's pagelet but HP website says it's page... which is the correct?
and btw, if i do the calculation for all the process, i believe the physical memory size for total process is beyond the physical memory for the alpha machine...

To david
as you said, the pages in working set are not physically in the memory at all.
i lost my way... if it's true, how to know how many physical memory a process uses ??(return to the original question, hehe)

Re: How to get dynamic memory information from another running process?

Davor_7 — Mon, 23 Jan 2006 02:44:57 GMT

Hi Halle,

i target the service manual...
so i think maybe the words on HP website is suitable to VAX (cannot say it's wrong...)

thanks~

now i'm confused with what David said... the pages in working set are not all physically in the memory
do you have any idea?

Re: How to get dynamic memory information from another running process?

Volker Halle — Mon, 23 Jan 2006 02:57:36 GMT

Davor,

terminology around pages/pagelets can sometimes be confusing, if you consider the 3 different architectures OpenVMS is running on.

From the IDSM (OpenVMS Internals and Datastructures Manual - Chapter 19):

The term working set refers to the virutal pages of a process that are currently valid and in physical memory.

And let's ask again: what is the problem your're trying to solve ? Is there a real problem ?

Volker.

Re: How to get dynamic memory information from another running process?

David B Sneddon — Mon, 23 Jan 2006 03:07:09 GMT

Yes, working set is a Volker states (my error).
This question has been asked in comp.os.vms and
I am trying to find an answer I remember seeing
that describes the situation very, very clearly.
I will post the link if I can find the article.

Re: How to get dynamic memory information from another running process?

Davor_7 — Mon, 23 Jan 2006 03:08:52 GMT

it's a performance problem
we will do a improvement which will cause many new process to run on the system. regard to the physical memory i wanna confirm whether the change can be implemented.

btw, do you have the soft copy of IDSM (OpenVMS Internals and Datastructures Manual) ? i cannot find it in the web...

and also, you mentioned:
The term working set refers to the virutal pages of a process that are currently valid and in physical memory.
my understand is that the size of working set(pagelet) is equal to the consumption of physical memory, is that correct?

Re: How to get dynamic memory information from another running process?

Davor_7 — Mon, 23 Jan 2006 03:10:56 GMT

thanks David,

very looking forward to your link...

Re: How to get dynamic memory information from another running process?

Volker Halle — Mon, 23 Jan 2006 03:34:51 GMT

Davor,

the IDSM is a book from Digital Press, that you need to buy (ISBN 1-55558-120-X).

The working set is made up by process private and global page(let)s. If you will create a lot of new processes (of the same type and memory usage charateristics), you could expect the physical memory usage to increase by times .

Consider to use SYS$EXAMPLES:WORKING_SET.COM and modify it to also print PPGCNT and GPGCNT.

Volker.