We have been fighting this problem for 4 years using uClinux 2.4. Upgrading to uClinux 2.6 is not an option for me right now. It really helps if you write all of your apps in C and statically allocate all of your memory. You can make programs that reload often "execute in place". Another trick is to use bget on a per program basis to allocate a chuck of memory for that app, and let bget manage it.
Farrell On Wed, Feb 11, 2009 at 3:25 AM, Jamie Lokier <ja...@shareable.org> wrote: > Andrei Martynov wrote: > > Tuesday, February 10, 2009, 1:27:53 PM, Jamie Lokier wrote: > > > > > The problem you have isn't really that it uses all memory for disk > > > cache - that's a good thing > > > > I believe that any continuos memory (re)allocation is evil on nommu > > platform with limited resources and should be avoided. > > > > How do others solve memory fragmentation problem? > > In general it's a hard problem. > > On no-MMU, Linux 2.4 mostly solved it with page_alloc2.c at some cost > to performance. But even that doesn't work if you have something > streaming large files from disk - additional tweaks are required, and > they aren't completely reliable. > > There have been some efforts to solve memory fragmentation on big > servers (with MMU) in Linux 2.6. Distinguishing short-lived and > long-lived pages is part of that, so is moveable pages (I don't know > if that fully works), and something called "lumpy reclaim". > > That's why I suggested trying a later kernel than 2.6.24, because some > anti-fragmentation patches are in .26, .27, .29-rc4 etc. (Just > download the ChangeLog files from kernel.org and you'll see > fragmentation mentioned). > > Some anti-fragmentation patches aren't in the mainline kernels yet. > > I don't know if the server anti-fragmentation code is effective on a > smaller no-MMU device. It's worth trying. > > -- Jamie > _______________________________________________ > uClinux-dev mailing list > uClinux-dev@uclinux.org > http://mailman.uclinux.org/mailman/listinfo/uclinux-dev > This message was resent by uclinux-dev@uclinux.org > To unsubscribe see: > http://mailman.uclinux.org/mailman/options/uclinux-dev >
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