Messages in this thread | | | From | Con Kolivas <> | Subject | Re: [PATCH] mm: implement swap prefetching | Date | Wed, 8 Feb 2006 16:06:19 +1100 |
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On Wed, 8 Feb 2006 03:46 pm, Paul Jackson wrote: > Con, responding to Nick: > > > It introduces global cacheline bouncing in pagecache allocation and > > > removal and page reclaim paths, also low watermark failure is quite > > > common in normal operation, so that is another global cacheline write > > > in page allocation path. > > > > None of these issues is going to remotely the target audience. If the > > issue is how scalable such a change can be then I cannot advocate making > > the code smart and complex enough to be numa and cpuset aware.. but then > > that's never going to be the target audience. It affects a particular > > class of user which happens to be quite a large population not affected > > by complex memory hardware. > > How about only moving memory back to the Memory Node (zone) that it > came from? And providing some call that Christoph Lameters migration > code can call, to disable or fix this up, so you don't end up bringing > back pages on their pre-migration nodes?
Sounds good, and this is what I was hoping to be able to do; first I need to see the best time and place to get this information (and learn some more about the code).
> Just honoring the memory node placement should be sufficient. No need > to wrap your head around cpusets.
Phew.
> If you don't do that, then consider disabling this thing entirely > if CONFIG_NUMA is enabled. This swap prefetching sounds like it > could be a loose canon ball in a NUMA box.
That's probably a less satisfactory option since NUMA isn't that rare with the light numa of commodity hardware.
> As for non-NUMA boxes, like my humble desktop PC, I would -love- > to have Firefox come back up faster in the morning. I have a nightly > cron jobs push everything out to swap, and it is slow going getting it > back. > > The day will come (it has already gotten there for some of my > colleagues who are using a small Altix system for their desktop > software) when we want this prefetching for NUMA boxes too.
I do see that now. Thanks for your comments too.
Cheers, Con - 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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