Messages in this thread |  | | Subject | Re: [ Matthias Sattler ] Bad 1.3.95 interactive performance (fwd) | Date | Tue, 30 Apr 1996 10:27:57 +0200 (MET DST) | From | Matthias Sattler <> |
| |
Hohi
> > > In your message dated: Mon, 29 Apr 1996 20:39:41 +0200 > >In addition to that, I'm a bit alarmed because no one else seems to see this > >problem :-( > > Well, looking at the output of free, it looks to me like you don't have > enough physical memory for you set up. And, considering you seem to have > a single disk, I am amazed (in a sense) that the disk head is not protruding > from the side of your machine by now! >
I use this setup (with this virtual memory usage) since 7 or 8 months without any performance problems. I can even start a kernelcompile and still work nicely. It seems that much of the virtual memory allocated is never used. In addition to that everything works fine after a reboot, the problems appear after some inactive!! (just the usual cronjobs) hours.
> I am sure that most people on this list understand the concepts of swapping > and paging. What some people might not understand are the issues with the > use of VM, the number of partitions your disk(s) has/have and the disks > that have swap space on them verses those that have swap and active text > on them.
I've put swap in the middle of the disk to minimize head movement.
> > In recent times, it was decided that there was no reason to swap text > (remember the sticky bit) because it was faster to just tell the VM manager > that the memory for text was free and read it back from the original disk > location later (text file busy scrolling up the screen...) > > The problem is that by doing this, the disk I/O for an active system that > is using VM to manage the address space(s) must now traverse a larger physical > surface area to get the text for all the active programs and then go back to > the swap partition to read/write data, than it did when it was all in one > partition! So, when you have a single disk and swapping starts, you can bet > that it could take quite some time to accomplish the VM shuffle required to > handle all of the address spaces that are active. > > My machine has 2 1GB scsi disks (CONNORs), and 1 2GB IDE disk (MAXTOR). > The day that I moved all of my swap to the IDE, I decided I did not need > more phsical memory. It used to take 10-15secs to switch virtual desktops > in fvwm. Now it takes 2-3secs! And that it swaping from a file that is > located on a fat file system. > > It might be interesting to turn off the special case for text some day > and see what happens to swapping when the head can hover over a single > partition again! > > Ever heard of a paging drum? If you know someone who has one of those really > small SCSI or IDE drives (40-200 megs), you might think about picking one up > and using it for your swap partition. It will at least keep the head from > having to consistantly wander around between text and data sources during > swapping. And maybe, like it did for me, you'll get a sizeable performance > improvement without having to buy more physical RAM (which I think is the > source of your wild swapping problem).
I've though about buying a disk to swap on, but I never really did it because system performance was ok for me.
> > ----- > gregg@lucent.com (Gregg Wonderly) > > Matthias
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