Messages in this thread | | | From | "Tom Leete" <> | Subject | Re: [VFS] move active filesystem | Date | Thu, 20 May 1999 21:58:05 -0400 |
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>On Thu, May 13, 1999 at 03:48:42PM -0600, WANG,YIDING (HP-SanJose,ex1) wrote: >> Linux has DMA memory allocation limitation to max. 128K - 24 bytes. >> Does anyone know how to break the limitation in driver to allocate more DMA >> memory, say 256K? > >And what about a more inteligent DMA memory allocator ? I mean, in case >of fragmented memory it's very frequent not to success to allocate DMA >memory by kernel (eg by sound/floppy modules). Why does not kernel >moves some memory, changing some pagetable entries etc to create >contigous memory area suitable for DMA (in low 16M for ISA DMA, care of >page boundaries etc). If there's enough memory to do it, it would be >only some memory moving action to get the suitable place. > >(I don't know too much about Linux kernel internals, maybe DMA memory >allocating is something atomic operation which blocks the kernel too long >to do such an operation I described below ?) > >Thanx : Gabor, >
Welsh's bigphysarea is less intellegent, not more, but you might look at: http://web.mountain.net/~tleete/bigphysarea-config-2.2.9-patch.gz which applies fairly clean to any 2.2.x or http://web.mountain.net/~tleete/bigphysarea-config-2.3.3.gz
It works by grabbing memory before the vm subsystem starts, and using its own private allocators. No swapping involved, relieves vm of a lot of incipient thrashing.
Regards, TML
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