Re: kernel page size explanation

[Gaspar Bakos <gbakos@cfa.harvard.edu>]

Hi, Jesper,

RE:
> > 2. how can one tune it (for 2.6.*)?
>
> For some archs the page size can be set at compile-time with
> CONFIG_PAGE_SIZE_4KB, CONFIG_PAGE_SIZE_8KB etc - mips is an example of
> such an arch (also take a look at CONFIG_HUGETLB_PAGE and friends).

OK, now i figured it out. On AMD opteron 64 bit processors the only
option is the default: 4Kb. For itanium and mips, indeed, there are
multiple options. My CPUs are opteron 64 bit ones; that is why i was
not able to find this feature (of tuning it).

> > How can i figure out the page size of the kernel i am currently using?
> >
> You can
>  A) look in the .config file for your current kernel (if your arch
> supports different page sizes at all).

Not there.

>  C) You can look at /proc/cpuinfo or /proc/meminfo , IIRC some archs
> report page size there - not quite sure, can't remember...

Probably not in meminfo, but possibly in cpuinfo:

cat /proc/cpuinfo
...
TLB size        : 1024 4K pages
...

cat /proc/meminfo
MemTotal:      4010956 kB
MemFree:       3848060 kB
Buffers:             0 kB
Cached:          45696 kB
SwapCached:          0 kB
Active:          90432 kB
Inactive:         4820 kB
HighTotal:           0 kB
HighFree:            0 kB
LowTotal:      4010956 kB
LowFree:       3848060 kB
SwapTotal:     7823576 kB
SwapFree:      7823352 kB
Dirty:              20 kB
Writeback:           0 kB
Mapped:          78668 kB
Slab:            46216 kB
CommitLimit:   9829052 kB
Committed_AS:   142036 kB
PageTables:       3252 kB
VmallocTotal: 34359738367 kB
VmallocUsed:      5724 kB
VmallocChunk: 34359732179 kB
HugePages_Total:     0
HugePages_Free:      0
Hugepagesize:     2048 kB

Cheers
Gaspar
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