harish@ece-csc.UUCP (Harish Hiriyannaiah) (03/18/89)
I am experiencing a wierd problem on our Microvax running Ultrix 2.2. One of the processes is hogging (70 %) a lot of memory and the system is definitely thrashing. Now, why should other processes get a "ran out of memory" error ? What is the virtual limit of memory on processes in Ultrix ? Why should it run out of memory if the os is a virtual memory machine ? ______________________________________ ____________________________________ | | ___ __ _ ___/ \/ | | -=====' _____ / \ ' \ / \ | /\ || I am not. Therefore I think not? | | / \/ \ \----| | | \_/\/ \/ || | | | || | | | |\_/ __/| || harish pu. hi. | | | || | | | | / | || harish@ece-csc.ncsu.edu | | \_____/\_____/ \____/ `_ \__/ || {b-bone sites}!mcnc!ece-csc!harish | \______________________________________/\____________________________________/
scs@adam.pika.mit.edu (Steve Summit) (03/18/89)
In article <3965@ece-csc.UUCP> harish@ece-csc.UUCP (Harish Hiriyannaiah) writes: >One of the processes is hogging (70 %) a lot of memory and the system is >definitely thrashing. Now, why should other processes get a "ran out of >memory" error ? Why should it run out of memory if the os is a virtual memory >machine ? There is no such thing as a free lunch. Virtual memory is mapped to disk blocks in swap space; your problem is almost certainly that you are out of swap space. (This can definitely be a rude surprise; I can remember getting "nroff: too big" on a VM machine and having flashbacks to my pdp11 days...) Swap space problems are frequent when "worksatations" with relatively small disks are pressed in to service as timesharing machines. Steve Summit scs@adam.pika.mit.edu
guy@auspex.UUCP (Guy Harris) (03/21/89)
>Why should it run out of memory if the os is a virtual memory >machine ? Well, you're the second person to ask that question recently.... "Virtual" memory ultimately has to be backed by "real" storage of some sort, in most cases. (We rule out the case of e.g. a system wherein a page fault on some locations in the address space causes the page fault handler to, for example, supply computed data rather than data from a file.) Therefore, if you run out of secondary storage to back up your virtual memory, you run out of virtual memory. You probably just ran out of swap space.