Hi,
I have a problem with a large process (a Fortran77/90 program) running
on a Digital Alphastation under UNIX V4.0B. The total amount of RAM is
128 Mbytes.
When I run the process there is a large amount of thrashing to disk.
If I use the command "ps v" to examine what is happening, it indicates
that the process is using only 64 % of memory. Does this number (%MEM)
indicate the total amount of RAM that the process is using? If it does,
is this a hard limit, or can I increase the use of RAM and hopefully
reduce the thrashing/paging to disk ?
For the moment I am the only user on the system, and there is no other
large process running. I have tried modifying the default "vm" and "proc"
attributes in the kernel's sysconfigtab file, but have not been able to
change the %MEM value by more than a few percent. Maybe I am not tuning
the correct parameters, or I am not modifying them correctly. Could
someone give me some advice ?
Swap is set to "lazy"(overcommitment) mode.
Below are two examples of the output of the "ps v" and "vmstat"
commands (the same process, but taken at slightly different moments in
time) as well as the output of the "swapon -s" command.
-------------------------------
ps v:
PID TTY S TIME SL PAGEIN VSZ RSS %CPU %MEM
743 ttyp0 R + 1:12.74 0 8273 227M 81M 98.2 64.1
PID TTY S TIME SL PAGEIN VSZ RSS %CPU %MEM
743 ttyp0 U + 1:54.79 0 22504 228M 84M 2.0 66.8
--------------------------------
vmstat:
Virtual Memory Statistics: (pagesize = 8192)
procs memory pages intr cpu
r w u act free wire fault cow zero react pin pout in sy cs us
sy id
3 64 18 12K 147 1552 76K 12K 31K 20K 20K 5911 139 1K 553 22
6 72
procs memory pages intr cpu
r w u act free wire fault cow zero react pin pout in sy cs us
sy id
2 64 19 12K 34 1533 100K 12K 31K 54K 43K 10K 144 794 585 18
4 77
---------------------------------
swapon -s:
Total swap allocation:
Allocated space: 62500 pages (488MB)
In-use space: 21806 pages ( 34%)
Available space: 40694 pages ( 65%)
----------------------------------
Any advice or suggestions would be much appreciated.
Craig.
---------
Craig.Brescianini_at_syd.dbce.csiro.au
Received on Thu May 08 1997 - 02:09:23 NZST