Re: Want to allocate almost all the memory with no swap

[James A. Sutherland <jas88@cam.ac.uk>]

On Thu, 19 Apr 2001 17:58:38 +0200 (MEST), you wrote:

>On Thu, 19 Apr 2001, James A. Sutherland wrote:
>
>> On Thu, 19 Apr 2001 17:39:23 +0200 (MEST), you wrote:
>> 
>> >Hi,
>> >
>> >I'm currently trying to run a high-performance bench on a cluster of PCs
>> >under Linux. This bench is the Linpack test, and needs a lot of memory to
>> >store a matrix of numbers. Linpack needs to allocate as much as 240 Megs
>> >on a machine that has 256 Megs of RAM, but I have to be sure that the
>> >memory used by linpack will never be swapped on the disk.
>> 
>> Call mlockall() to lock all your memory into physical RAM - there's a
>> flag to set which ensures all your future allocations are locked as
>> well. You should be left with 16 Mb of physical RAM free, plus swap,
>> so you should be able to do this as long as the machine isn't too
>> heavily loaded at the time - no running Netscape during benchmarks :-)
>
>Well, I have removed as many processes deamons as I could, and there are
>not many left.
>But under both 2.4.2 and 2.2.17 (with swap on)I get, when I run my
>program:
>
>mlockall: Cannot allocate memory

Hrm? Can you trim the consumption a bit - try cutting a big chunk out,
like 64 Mb, and see if it works then?


James.
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