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shlomoid
Asked: 2011-05-18 01:08:51 +0800 CST

Solaris 10: What does "Page cache" stand for in "echo ::memstat | mdb -k"

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When running "echo ::memstat | mdb -k" I get this result:

Page Summary                Pages                MB  %Tot
------------     ----------------  ----------------  ----
Kernel                    2349789              9178   14%
ZFS File Data             4251652             16608   25%
Anon                      8101424             31646   48%
Exec and libs               51583               201    0%
Page cache                1018684              3979    6%
Free (cachelist)             5049                19    0%
Free (freelist)            992659              3877    6%

Total                    16770840             65511
Physical                 16323297             63762

Everything I read online says that the the file system caching layer (ARC) in ZFS is "ZFS File Data". What does "Page cache" stand for? Why is it so large then?

I'm sorry if this is a basic question, but no google search I tried turned up any reasonable results.

solaris memory-usage

3 Answers

  1. Best Answer

    Even when installed with a ZFS root disk, Solaris systems still make use of other filesystems that are not ZFS. For instance, tmpfs will use the VM page cache.

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  2. The Page cache is the file system cache for non ZFS file systems. It's size will be as big as the system thinks it needs to be.

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  3. The page cache is for non ZFS file system (i.e. for example UFS) caching. I suspect you are not 100% ZFS.

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