Dear List,
According to the following Red Hat KB, it seems that the default
value, which goes to "100",
means that all the physical memory pages could 'possibly' be used as a
pagecache.
- DOC-2131
http://kbase.redhat.com/faq/docs/DOC-2131
It is to my curiousity that even I lower the value to '10', pagecache
will still try to fill all the
memory pages out.
Here is how I made the test.
<Test1>
[r...@kijima ~]# sysctl -w vm.pagecache=10;dd if=/dev/zero
of=/tmp/001.tmp bs=1M count=4096;free -m;rm -f /tmp/001.dmp;free -m
vm.pagecache = 10
4096+0 records in
4096+0 records out
4294967296 bytes (4.3 GB) copied, 27.8518 seconds, 154 MB/s
total used free shared buffers cached
Mem: 3072 3062 9 0 14 2617
-/+ buffers/cache: 430 2641
Swap: 2047 0 2047
total used free shared buffers cached
Mem: 3072 370 2701 0 14 45
-/+ buffers/cache: 310 2761
Swap: 2047 0 2047
The result above makes no big difference when the 'pagacache' value is
set to the default '100'.
<Test2>
[r...@kijima ~]# sysctl -w vm.pagecache=100;dd if=/dev/zero
of=/tmp/001.dmp bs=1M count=4096;free -m;rm -f /tmp/001.dmp;free -m
vm.pagecache = 100
4096+0 records in
4096+0 records out
4294967296 bytes (4.3 GB) copied, 27.5054 seconds, 156 MB/s
total used free shared buffers cached
Mem: 3072 3061 10 0 16 2627
-/+ buffers/cache: 416 2655
Swap: 2047 0 2047
total used free shared buffers cached
Mem: 3072 369 2702 0 16 45
-/+ buffers/cache: 307 2764
Swap: 2047 0 2047
I am just wondering if there were anything I missed to make it work right.
--
Sincerely,
Jyo
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