Re: [RFC] Limit the size of the pagecache

[Vaidyanathan Srinivasan]

Christoph Lameter wrote:
> On Wed, 24 Jan 2007, Erik Andersen wrote:
> 
>> It would be far more useful if an application could hint to the
>> pagecache as to which files are and which files as not worth
>> caching, especially when the application knows a priori that data
>> from a particular file will or will not ever be reused.
> 
> It can give such hints via madvise(2).

I think you meant fadvise.  That is certainly a possibility which we
need to work on.  Current implementation of fadvise only throttles
read ahead in case of sequential access and flushes the file in case
of DONTNEED.  We leave it at default for NOREUSE.

In case of DONTNEED and NOREUSE, we need to limit the pages used for
page cache and also reclaim them as soon as possible.  Interaction of
 mmap() and fadvise is little more dfficult to handle.

--Vaidy

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