Re: [VFS] move active filesystem
Tom Leete (tleete@access.mountain.net)
Thu, 20 May 1999 21:58:05 -0400
>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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