Messages in this thread | | | Subject | Re: Odd swapping issue | From | Peter Zijlstra <> | Date | Thu, 24 Jul 2008 15:58:51 +0200 |
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On Thu, 2008-07-24 at 15:45 +0200, Rafal Wijata (NULL) wrote: > OK, things are little more clear now I suppose. > > I tried (just for fun) echo 8 > /proc/sys/vm/nr_hugepages > and it happened again, and no hugepages were allocated of course. > > But this brought the following to my mind. > > Since it's nfs server/client, and the nfs is rather heavily utilized(at > least sometimes), maybe nfsd tasks were unable to find long enough lowmem > chunk. How can we get such ram? By sweeping pages out to swap, isn't it? > > Now the question is, if Linux actually has such feature like blind swapping > out if lowmem is too fragmented to find requested size? > Can anybody confirm or negate?
Well, not blind - we have lumpy reclaim that tries to focus on the right spot for large order allocations. However there are a myrad of conditions that can make it impossible to reclaim certain pages, therefore defeating this strategy.
> Next, I was thinking then I could run 64bit system, but I don't want to > reinstall it. Anybody knows if it's possible to have installed 32bit OS, but > run 64bit kernel alone(no 64bit glibc or anything else)?
Yes running as I type ;-)
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