Re: Limit hash table size

[Andrew Morton]

Steve Lord <lord@xxxxxxx> wrote:
>
>  I have seen some dire cases with the dcache, SGI had some boxes with
>  millions of files out there, and every night a cron job would come
>  along and suck them all into memory. Resources got tight at some point,
>  and as more inodes and dentries were being read in, the try to free
>  pages path was continually getting called. There was always something
>  in filesystem cache which could get freed, and the inodes and dentries
>  kept getting more and more of the memory.

There are a number of variables here.  Certainly, the old
inodes-pinned-by-highmem pagecache will cause this to happen - badly.  2.6
is pretty aggressive at killing off those inodes.

What kernel was it?

Was it a highmem box?  If so, was the filesystem in question placing
directory pagecache in highmem?  If so, that was really bad on older 2.4:
the directory pagecache in highmem pins down all directory inodes.

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