Messages in this thread | | | Date | Thu, 29 Dec 2005 16:11:58 -0800 | From | Andrew Morton <> | Subject | Re: + drop-pagecache.patch added to -mm tree |
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Christoph Hellwig <hch@infradead.org> wrote: > > On Thu, Dec 29, 2005 at 05:54:08PM +0800, Coywolf Qi Hunt wrote: > > 2005/12/2, akpm@osdl.org <akpm@osdl.org>: > > > > > > The patch titled > > > > > > drop-pagecache > > > > > > has been added to the -mm tree. Its filename is > > > > > > drop-pagecache.patch > > > > > > > > > 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. > > d) it is a total mess.
Rubbish.
> A lot of code
295 bytes.
> for something that you shouldn't do > except for benchmarking.
Sure. It's a debugging feature.
> If people see problems where pagecache data isn't > dropped enough we should fix the VM instead of adding code that just bloats > the kernel more.
It's useful for debugging VM problems, too.
I'm not fussed, really - it's useful for kernel developers and testers. If we're so worried about a very small amount of not-at-all-messy code then we can stick it under CONFIG_DEBUG_VM. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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