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From: veit@du9ds3.uni-duisburg.de (Holger Veit)
Newsgroups: comp.unix.bsd
Subject: Re: stock 0.1 swap not enough.
Keywords: swap
Message-ID: <veit.712998619@du9ds3>
Date: 5 Aug 92 07:10:19 GMT
References: <BsDzMo.1ru@chinet.chi.il.us> <BsFMoo.EvF@obiwan.uucp> <1992Aug4.162010.16364@mks.com>
Sender: @unidui.uni-duisburg.de
Reply-To: veit@du9ds3.uni-duisburg.de
Organization: Uni-Duisburg FB9 Datenverarbeitung
Lines: 66
In <1992Aug4.162010.16364@mks.com> fredw@mks.com (Fred Walter) writes:
>bob@obiwan.uucp (Bob Willcox) writes:
>>randy@chinet.chi.il.us (Randy Suess) writes:
>>> Well, I now have proof that the stock 5 meg swap partition
>>> created with the 0.1 install disk is not enough. I added
>>> a second disk and gave it another 5 megs of swap (I have
>>> 8 megs memory) using swapon.
>>
>>How does one go about increasing the swap size when you only have a
>>single disk? Is there a way to do this without re-installing?
>No, you'll have to re-install. What I plan on doing (once my system is
>more stable) is backing up my system with cpio, then using the Fixit disk
>(and an editted /etc/disktab on the Fixit disk that has a correct swap size
>entry) to re-disklabel my primary hard disk, re-format my partitions and then
>restore from tape.
>I've seen several formulas for calculating the correct amount of swap.
> - one person said 2*physical_memory*1.1
> - one person said 2*physical_memory*1.5
>So, which is it ? I'd rather not waste more harddisk space than necessary on
>a too-big swap partition (I have 12 meg RAM; 2*12*1.1=26.4; 2*12*1.5=30)
>because I'm currently running without a swap partition and my system hasn't
>seemed to need one. But I want to run X386 and those binaries are *hugh* so
>I'll need some swap space. (And more memory, and more hard disk space...)
> fred
>--
>Disclaimer: everything I write is my *personal* opinion and does not represent
>or reflect the opinion of the company which employs me.
As already someone mentioned: The request for a formula depending on available
RAM is incorrect. The formulae N*phys_mem is a rule of thumb and may or may not
fit your requirements. I also read in the SUNOS Manuals to use 2*physmem+10%,
but this has been calculated (or guessed?) for an average usage profile. The
swap space depends at least on:
- The number of processes you want to run
- the space requirement these processes have (you know "EMACS = eight
megabytes and continuously swapping" :-) )
BTW: on our Sun's we have some testpattern generation software which has
virtual space requirements of > 100 MB
- the number of users who use the system (notice that each window in X11
counts as a single user, again a rule of thumb)
- the number of simultaneous network connections
- the disk throughput (to make file access faster, you must add FS cache space,
this reduces available main memory, the system starts paging and swapping
earlier)
- ...
- ... There are more dependencies, look into a good book on operating systems
design.
The standard 5 MB swap space are sufficent in the environment of the files
of the bindist, provided you use your PC as a "work station" (not multi-user
machine).
X11 should have at least 16 to 32 MB (independently of how much RAM you have,
but you should not even think of X11 with less than 8 MB RAM). My $0.02.
Holger
--
| | / Holger Veit | INTERNET: veit@du9ds3.uni-duisburg.de
|__| / University of Duisburg | BITNET: veit%du9ds3.uni-duisburg.de@UNIDO
| | / Dept. of Electr. Eng. | "No, my programs are not BUGGY, these are
| |/ Inst. f. Dataprocessing | just unexpected FEATURES"