Messages in this thread | | | Date | Thu, 10 Sep 2009 00:39:02 +0900 | Subject | Re: [rfc] lru_add_drain_all() vs isolation | From | Minchan Kim <> |
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On Wed, Sep 9, 2009 at 1:27 PM, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote: >> The usefulness of a scheme like this requires: >> >> 1. There are cpus that continually execute user space code >> without system interaction. >> >> 2. There are repeated VM activities that require page isolation / >> migration. >> >> The first page isolation activity will then clear the lru caches of the >> processes doing number crunching in user space (and therefore the first >> isolation will still interrupt). The second and following isolation will >> then no longer interrupt the processes. >> >> 2. is rare. So the question is if the additional code in the LRU handling >> can be justified. If lru handling is not time sensitive then yes. > > Christoph, I'd like to discuss a bit related (and almost unrelated) thing. > I think page migration don't need lru_add_drain_all() as synchronous, because > page migration have 10 times retry. > > Then asynchronous lru_add_drain_all() cause > > - if system isn't under heavy pressure, retry succussfull. > - if system is under heavy pressure or RT-thread work busy busy loop, retry failure. > > I don't think this is problematic bahavior. Also, mlock can use asynchrounous lru drain.
I think, more exactly, we don't have to drain lru pages for mlocking. Mlocked pages will go into unevictable lru due to try_to_unmap when shrink of lru happens. How about removing draining in case of mlock?
> > What do you think? > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> >
-- Kind regards, Minchan Kim -- 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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