[uClinux-dev] uClinux page cache, pdflush and memory reclamation

Erjiang Li eli at netspectrum.com
Thu Jul 14 23:40:37 EDT 2011

I have some questions about uClinux page cache and memory reclamation.
Probably some one can give some advice here. Thanks in advance.

My platform: ARM dev board + uclinux 2.6.25

My questions:
If we limit the size of page caches or increase the write-back frequency for
dirty data in page caches, can we avoid/decrease the frequency of OOM-Killer
occurrence in the case of kernel memory being in pressure? I know the page
cache is tunable, but is it helpful if I just want to avoid OOM-Killer
happens. The implementation of page allocation function in kernel (i.e.
__alloc_pages() in mm/page_alloc.c ) has called wakeup_kswapd()  when
get_page_from_freelist() function can't return a valid page, I don't know
whether this function starts pdflush thread to reclaim memory? If so, does
it indicate that it's not necessary for us to tune page caches?  And is the
tuning operation on page cache only for write-heavy loads, not for memory

Best Regards

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