Messages in this thread | | | Date | Tue, 19 Sep 2000 11:03:23 +0200 | From | Helge Hafting <> | Subject | Re: Very aggressive swapping after 2 hours rest |
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Byron Stanoszek wrote: > > I've finally had a chance to test out the new VM patch on my 32mb system. > > It runs much, much better than the previous test8, and the pages->swap change > is actually much smoother than I had expected it to be considering the recent > talk about making it more gradual. I'm against having the swap more gradual > because of the low amount of available memory and the high amount of memory > actually taken up by processes required for normal operation. > > At the moment, there's only room for about 5-6 meg of cache. If a gradual swap > goes into effect, then I'm afraid that the processes that actually 'need' to > stay in memory will start swapping out and thrashing, even when there's 6 meg > still available for use. This was precisely the problem with the old VM on my > machine, only the system wanted to keep 16 meg free for cache (*gag*).
I hope we can have a swap mechanism that gradually writes stuff into swap early on, but don't actually unmap the memory. So we get clean pages that are still available but may be dropped quickly if needed. This will smooth things a bit without degrading performance.
Some memory should be kept around for cache (if the processes do any io at all) or you'll get io trashing: the same stuff read over and over from files instead of from cache. And a read before every write that isn't a complete block.
Almost all processes have some pages they don't use much, such as startup initialization. Swapping out that doesn't hurt.
Helge Hafting - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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