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On Thu, Mar 23 2006, Con Kolivas wrote: > Jens Axboe writes: > > >It's a heuristic, and sometimes that will work well and sometimes it > >will not. What if during this period of inactivity, you start bringing > >everything in from swap again, only to page it right out because the > >next memory hog starts running? From a logical standpoint, swap prefetch > >and the vm must work closely together to avoid paging in things which > >really aren't needed. > > If the system is idle it doesn't cost anything to bring those pages in > (laptop mode disables any prefetching if you're thinking about power > consumption on laptops). And if the system wants the ram that has been > filled with prefetched pages wrongly, the prefetched pages are at the tail > end of the inactive LRU list with a copy on backing store so if they're not > accessed they'll be the first thing dropped in preference to anything > else, without any I/O. I missed the fact that you left these pages on backing store for easy dropping in the future. I guess if you didn't, it could coarsely be handled in user space easily. -- Jens Axboe - 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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