Swapping and wmgr

John B. Milton jbm at uncle.UUCP
Sun May 29 07:22:17 AEST 1988


In article <3030 at crash.cts.com> ford at crash.CTS.COM (Michael Ditto) writes:
>In article <459 at bacchus> darren at bacchus.UUCP (Darren Friedlein) writes:
>>In article <153 at elgar.UUCP> ford at kenobi.UUCP (Mike Ditto) writes:
>>>In article <449 at bacchus> darren at bacchus (Darren Friedlein) writes:
...
>The Unix PC supports 4M of virtual memory PER PROCESS, with a total amount
>dependant on your physical memory + swap space.

I read somewhere in the docs that the UNIXpc actually limits each process to
2.5M virtual. It could not be as high as 4.0M because the kernel ALWAYS takes
up some 340k+. Then there are loadable drivers, etc. If user processes were
allowed to get near 4M, they could easily force the machine into constant
thrash and eventual crash.

I just whipped up a quicky, and here's what I got (2.5M=2609152)

max allocate ~= 2535424

main()
{
	int first,last,old;

	first=sbrk(0);
	while ((old=sbrk(4096))!=-1)
		last=old;
	printf("max allocate ~= %d\n",last-first);
}

John
-- 
John Bly Milton IV, jbm at uncle.UUCP, {ihnp4|osu-cis}!n8emr!uncle!jbm
home: (614) 294-4823, work: (614) 459-7641; talk to me about fractals



More information about the Comp.sys.att mailing list