Messages in this thread |  | | Date | Wed, 12 Feb 1997 10:04:14 -0200 (GMT+2) | From | Bennie Venter <> | Subject | re: Big mallocs, mmap sorrows and double buffering. |
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On Tue, 11 Feb 1997, John Carter wrote:
> On Mon, 10 Feb 1997, Mark Hahn wrote: > > > use mmap! it's _easier_ than malloc/read, and better yet, is also > > _optimal_ when confronted with changing memory loads. and of course > > it also happens to be significantly more efficient, since you get > > buffer-cache blocks mapped directly into your address space: > > your disk controller reads them into memory, and you get to see > > them, no silly copying from kernel to user-space. > > > > let me know if you need some code on mmap. I use it extensively. > > Sounds like just what I need. > > Hmm. I remember using a facility like this on the old vaxen. The > glitch was if I mapped an entire satellite image (+-400megabytes) the > page tables used up so much physical memory that the thing started > thrashing again. (There we just settled down to using two 32k buffers > and doing NO_WAIT read/writes.) >
I do not know how the linux kernel handles it, but did you ever consider using memory mapped files - this way only the portions you work on is in memory much like the demand-paged executables. I do assume you are working on very big files here.
Tnx & Bi Bennie Venter
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