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SubjectOOM killer very aggressive on 2.4.15.pre7

I am running my memory management tests (ltp.sf.net under
testcases/kernel/mem/...) on linux-2.4.15.pre7i, trying to stress it. I
notice that the OOM killer is very aggressively killing my processes.

The tests can be found on ltp web site, ltp.sf.net, under
.../testcases/kernel/mem/... and
.../testcases/kernel/network/nfs/nfsstress/...

I try to stress VMM by doing the following.

1) mmap a file of size = sizeof(char) * 1000000000; as shared and private
mapping.

2) mmap the same size as anonymous memory, private and shared.

3) mmap a file of same size shared.

4) memory race conditions tests.

5) spawn 30 threads, each thread mallocs memory in a loop size is either
powers of 2,3,or 7 or size = numbers in fibbanoci series. (see source
mallocstress.c for details on ltp.sf.net)

6) Also I am generating a lot of disk I/O and compiles (invoking cc) by
running my make_tree (NFS client) test over NFS. (details about the test
available in the source
.../testcases/kernel/network/nfs/nfsstress/make_tree.c.)

machine configuration is:
kernel: 2.4.15.pre7(SMP)
Total Memory: 9GB
Total Swap: 5GB
HDD: 14GB
CPU: 2 way, pentium III coppermine
Himem: set to 4GB

I did not notice such aggrasivness in the OOM killer when I was running
the same on linux-2.4.15.pre6. The results of that test are available
towards the end. The tests that do the mmap's were being killed most
often, even if I restart them (now it becomes the most recently used) it
still gets killed. I was running the same number of test on 2.4.15.pre6
and OOM was not this aggressive.

When I try to restart the mmap tests, mmap() compilains out of memory, and
is eventually killed. The machine memory statistics that instant are as
follows (reported by top refreshing every 2 sec).

Mem: 1029356K total, 1023836K used, 5520K free, 232K buffers
Swap: 538136K total, 511432K used, 26704K free, 927712K cached

I have now overloaded the machine by running the mmap tests in a infinite
while loop. So that it will restart if killed by the OOM killer. Also,
assuming that I will bring the swap free to zero, I did succede in
bringing swap free to zero, and the VMM did a good job by killing some
processes and keep the machine running. This is a major improvement over
2.4.13 where the machine would just hang (do nothing!).

I will let these tests run for 24hrs and I will post my test results
tomorrow(11/21/2001). If someone has any suggestion or require some
different statisitcs from these tests please email me so that I can post
that too. My email at work is manjo@austin.ibm.com and that at home is
manjo@austin.rr.com.

The results of VMM tests on 2.4.15.pre6 on SMP is as follows.

Kernel: 2.4.15.pre6 (SMP)
Total mem: 9GB
Total Swap: 5GB
Total CPU: 2 way, (Pentium III coppermine)
Total exec time: 24Hrs


CPU utilization
~~~~~~~~~~~~~~~
09:11:22 CPU %user %nice %system %idle
Average: 0 16.66 0.00 59.60 23.74
Average: 1 16.40 0.00 59.89 23.71
average: all 16.53 0.00 59.74 23.73

I/O and transfer rate statistics
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
09:11:22 tps rtps wtps bread/s bwrtn/s
Average: 92.74 50.96 41.78 2814.52 12581.92

paging statistics.
~~~~~~~~~~~~~~~~~~
09:11:22 pgpgin/s pgpgout/s activepg inadtypg inaclnpg inatarpg
Average: 1407.26 6290.88 34395 0 0 0

process creation activity.
~~~~~~~~~~~~~~~~~~~~~~~~~~
09:11:22 proc/s
Average: 17.09

activity for each block device
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
09:11:22 DEV tps blks/s
Average: dev8-0 92.74 15396.44


queue length and load averages
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
09:11:22 runq-sz plist-sz ldavg-1 ldavg-5
Average: 24 556 41.30 41.21

memory and swap space utilization statiscs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
09:11:22 kbmemfree kbmemused %memused kbmemshrd kbbuffers kbcached
kbswpfree kbswpused %swpused
Average: 121312 779068 86.53 0 9278 403342
305511 232625 43.23

memory statistics.
~~~~~~~~~~~~~~~~~~
09:11:22 frmpg/s shmpg/s bufpg/s campg/s
Average: 2.42 0.00 0.05 -1.35

system switching activity.
~~~~~~~~~~~~~~~~~~~~~~~~~~
09:11:22 cswch/s
Average: 52151.52o

swapping statistics
~~~~~~~~~~~~~~~~~~~~
09:11:22 pswpin/s pswpout/s
Average: 12.72 842.88

ksymoops -m /boot/System.map-2.4.15-pre6 /var/log/messages /var/log/kern.log
/var/log/syslog

ksymoops 2.4.3 on i686 2.4.15-pre6. Options used
-V (default)
-k /proc/ksyms (default)
-l /proc/modules (default)
-o /lib/modules/2.4.15-pre6/ (default)
-m /boot/System.map-2.4.15-pre6 (specified)

No modules in ksyms, skipping objects
Warning (read_lsmod): no symbols in lsmod, is /proc/modules a valid lsmod file?
Nov 19 10:40:46 corvette kernel: WARNING: MP table in the EBDA can be UNSAFE,
contact linux-smp@vger.kernel.org if you experience SMP problems!
Nov 19 10:40:46 corvette kernel: cpu: 0, clocks: 1332704, slice: 444234
Nov 19 10:40:46 corvette kernel: cpu: 1, clocks: 1332704, slice: 444234
Nov 19 10:40:47 corvette kernel: ds: no socket drivers loaded!
Nov 19 10:40:46 corvette kernel: WARNING: MP table in the EBDA can be UNSAFE,
contact linux-smp@vger.kernel.org if you experience SMP problems!
Nov 19 10:40:46 corvette kernel: cpu: 0, clocks: 1332704, slice: 444234
Nov 19 10:40:46 corvette kernel: cpu: 1, clocks: 1332704, slice: 444234
Nov 19 10:40:47 corvette kernel: ds: no socket drivers loaded!

1 warning issued. Results may not be reliable.


Nov 19 10:40:46 corvette kernel: Warning only 896MB will be used.
Nov 19 10:40:46 corvette kernel: Use a HIGHMEM enabled kernel.
Nov 19 10:40:46 corvette kernel: found SMP MP-table at 0009e1d0
Nov 19 10:40:46 corvette kernel: hm, page 0009e000 reserved twice.
Nov 19 10:40:46 corvette kernel: hm, page 0009f000 reserved twice.
Nov 19 10:40:46 corvette kernel: hm, page 0009e000 reserved twice.
co
ntact linux-smp@vger.kernel.org if you experience SMP problems!
Nov 19 10:40:46 corvette kernel: On node 0 totalpages: 229376
Nov 19 10:40:46 corvette kernel: zone(0): 4096 pages.
Nov 19 10:40:46 corvette kernel: zone(1): 225280 pages.
Nov 19 10:40:46 corvette kernel: zone(2): 0 pages.
Nov 19 10:40:46 corvette kernel: Intel MultiProcessor Specification v1.4
Nov 19 10:40:46 corvette kernel: Virtual Wire compatibility mode.
Nov 19 10:40:46 corvette kernel: OEM ID: IBM ENSW Product ID: NF 6000R SMP APIC
at: 0xFEE00000

Thanks
Manoj Iyer

*******************************************************************************
Linux Test Project WEB:ltp.sf.net
IBM, Austin TX.
email: manjo@austin.ibm.com
Phone: 512 838 4064
*******************************************************************************

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