Messages in this thread |  | | From | Systemkennung Linux <> | Subject | Re: Memory intensive processes | Date | Wed, 11 Dec 1996 17:47:05 +0100 (MET) |
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> > Consider you have a process with a very large set of matrices. Most of > > these could be sparse (eg mostly zeros). The IEEE representation of > > floating point zeroes is all zeroes. Therefore, the scheme you mention > > could in fact suitably represent in a single page a large chunk of memory > > that would otherwise be wasted (filled with zeroes). This alone could get > > some of the large process blues off of Linux' back. > > > This is true. Also the act of READING zero-filled pages should not cause > a trap to the operating system. Many FFTs null-fill a lot of RAM and > certainly never write to it.
Not a good idea. Implementing your suggestion would mean that large parts the page tables which are are just truncated off would have to be allocated and memory. Just mmaping 1gb from /dev/zero would cost you over 1mb of *not swappable* memory for page tables. Aside of that allocation and filling consumes a lot of time.
Better optimize the FFT ...
Ralf
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