Re: [PATCH] drop page cache of a single file

[Fengguang Wu]

On Wed, Dec 27, 2006 at 07:49:59PM -0800, Andrew Morton wrote:
> On Thu, 28 Dec 2006 11:17:25 +0800
> "Zhang, Yanmin" <yanmin_zhang@xxxxxxxxxxxxxxx> wrote:
> 
> > Currently, by /proc/sys/vm/drop_caches, applications could drop pagecache,
> > slab(dentries and inodes), or both, but applications couldn't choose to
> > just drop the page cache of one file. An user of VOD (Video-On-Demand)
> > needs this capability to have more detailed control on page cache release.
> 
> The posix_fadvise() system call should be used for this.  Probably in
> combination with sys_sync_file_range().

Yanmin: I've been using the fadvise tool from
http://www.zip.com.au/~akpm/linux/patches/stuff/ext3-tools.tar.gz

It's a nice tool:

% fadvise 
Usage: fadvise filename offset length advice [loops]
      advice: normal sequential willneed noreuse dontneed asyncwrite writewait
% fadvise /var/sparse 0 0x7fffffff dontneed

Regards,
Wu
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