Re: Better pagecache statistics ?

Frank Ch. Eigler
2005-12-02T22:15:18Z

Badari Pulavarty <pbadari@us.ibm.com> writes:

> > Can't you add hooks to add_to_page_cache/remove_from_page_cache
> > to record pagecache activity ?
>
> In theory, yes. We already maintain info in "mapping->nrpages".
> Trick would be to collect all of them, send them to user space.

If you happened to have a copy of systemtap built, you might run this
script instead of inserting static hooks into your kernel. (The tool
has come some way since the OLS '2005 demo.)

#! stap
probe kernel.function("add_to_page_cache") {
printf("pid %d added pages (%d)\n", pid(), $mapping->nrpages)
}
probe kernel.function("__remove_from_page_cache") {
printf("pid %d removed pages (%d)\n", pid(), $page->mapping->nrpages)
}

- FChE