Re: Where do you put your swap partition?
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On 01/23/08 18:37, Rick Thomas wrote:
>
> On Jan 23, 2008, at 4:27 PM, David Brodbeck wrote:
>
>>
>> On Jan 22, 2008, at 8:54 PM, Rick Thomas wrote:
>>
>>> The rule of thumb comes from UNIX days (BSD and even before that with
>>> AT&T UNIX). In order to be completely sure you would be able to swap
>>> out a program when memory became full, UNIX allocated a page of swap
>>> for every page of virtual memory a program occupied. So if vi
>>> required 256K to run, there was 256K of swap space allocated to it.
>>> The 2 to 1 ratio came from the observation that a busy UNIX
>>> time-sharing system with lots of users ran most of it's time with
>>> half the users doing something that required CPU/memory resources and
>>> the other half thinking, so you could afford to overcommit memory by
>>> a factor of two.
>>
>> Thanks for the interesting history lesson. :)
>
> You're welcome. It had the interesting side-effect that people
> developed the habit, after they were done thinking and wanted to start
> working on the computer again, of hitting the <return> key to "wake up
> the computer" (really, to initiate a bunch of swap-in operations) then
> wait several seconds for the cursor to actually return and the command
> prompt to re-appear. The swapping algorithms knew about this behavior
> and optimized for it. When a process group had been idle long enough to
> indicate the start of a "think" cycle, the whole process group was
> swapped out at once. When the user started up again, the whole process
> group was swapped in -- assuming that the user would be needing it soon.
>
> I'm really gettin' old!
Have you yet bitched and complained how kids today have it so much
easier, and don't appreciate what they have?
- --
Ron Johnson, Jr.
Jefferson LA USA
"I'm not a vegetarian because I love animals, I'm a vegetarian
because I hate vegetables!"
unknown
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