Messages in this thread | | | Subject | Re: [PATCH 0/4] linux-2.6-block: deactivating pagecache for benchmarks | From | Badari Pulavarty <> | Date | Fri, 02 Dec 2005 11:19:21 -0800 |
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On Thu, 2005-12-01 at 20:34 -0500, Jeff Garzik wrote: > On Thu, Dec 01, 2005 at 05:25:20PM -0800, Andrew Morton wrote: > > Dirk Henning Gerdes <mail@dirk-gerdes.de> wrote: > > > > > > For doing benchmarks on the I/O-Schedulers, I thought it would be very > > > useful to disable the pagecache. > > > > That's an FAQ. Something like this? > > > > > > From: Andrew Morton <akpm@osdl.org> > > > > Add /proc/sys/vm/drop-pagecache. When written to, this will cause the kernel > > to discard as much pagecache and reclaimable slab objects as it can. > > > > It won't drop dirty data, so the user should run `sync' first. > > > > Caveats: > > > > a) Holds inode_lock for exorbitant amounts of time. > > > > b) Needs to be taught about NUMA nodes: propagate these all the way through > > so the discarding can be controlled on a per-node basis. > > > > c) The pagecache shrinking and slab shrinking should probably have separate > > controls. > > > > > > Signed-off-by: Andrew Morton <akpm@osdl.org> > > ACK, I've wanted something like this for a while. > > I really think it should be a config option, though, to discourage > people from building with it :)
Why ? Since its controlled through /proc, if some one "echo" stuff into it, they might get crappy performance (like other /proc tunables). Isn't it expected ?
Thanks, Badari
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