Linux page cache is a shared resource which any process accessing the file can access. There is no mechanism within generic page cache handler to support such quota mechanism, as there is no meta information attached with the page in pagecache.
However it looks possible to me to implement it within a file-system by defining a wrapper structure above each page in page-cache which can hold per user information about the page. NFS maintains a wrapper structure nfs_page over dirty page-cache pages and maintains credentials of user within this structure. However purpose of doing so is for correctness and flush any incompatible pages to NFS server before writing new dirty page to page cache.
It feasible to implement such quota schemes, but may come up with some performance implications and maintenance cost will be high for such a code. But anyways, if you plan to implement such a file-system (or modify existing one), it can be a nice learning project. Infact many people keep looking for kernel project on this list, this looks to me a great idea for that matter.
Rajat
On Thu, Jan 6, 2011 at 3:25 PM, sanoj <k.u.sanoj@xxxxxxxxx> wrote:
> Hello
> my doubt is if linux has any user quota for the usage of page cache,
> i.e. if a user is doing a disk intensive operation, will the I/O performance
> for other users other users be affected as they
> may incur more cache misses.
> thanks,
> sanoj
>
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