Messages in this thread | | | From | Roger Larsson <> | Subject | Re: [PATCH][RFC] simpler __alloc_pages{_limit} | Date | Sat, 25 Aug 2001 18:25:19 +0200 |
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On Saturday den 25 August 2001 13:55, Stephan von Krawczynski wrote: > On Sat, 25 Aug 2001 02:48:28 +0200 > > Roger Larsson <roger.larsson@norran.net> wrote: > > Hi again, > > > > [two typos corrected from the version at linux-mm] > > [...] > > Doing this - the code started to collaps... > > __alloc_pages_limit could suddenly handle all special cases! > > (with small functional differences) > > > > Comments? > > Hi Roger, > > I tested your page against straight 2.4.9 (where it applied mostly, the > rest I did manually) and experience the following: > 1) system gets slow, even in times where plenty of free memory is > available. There must be some overhead inside.
It is not unlikely because it care too much about the higher order allocations. It needs a higher order page and really tries...
> 2) It does not really work around the basic problem of too > many cached pages in case of heavy filesystem action, I do get the already > known "kernel: __alloc_pages: 2-order allocation failed." by simply copying > files a lot.
Is this with raiserfs and/or nfs? And without highmem support? Why is 2-order allocations needed??? Can anyone answer? Higher order allocs during normal operation is not that nice...
> 3) Even in high load situations the CPU load seems to get > worse, I made it up to 7 with normal file copying on a SMP 1GHz 1GB RAM > machine.
Might also be related to the higher order. Freeing too much inactive pages to satisfy the request... SMP might be a factor since the patch will go harder on the locks...
> > Hm, I guess that doesn't really work as you expected.
Well, I make a version that gives up on higher order allocations more quickly...
But the real problem might be - why are the higher order allocations needed anyway?
/RogerL
-- Roger Larsson Skellefteå Sweden - 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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