From: obz@sisd.kodak.com (Orest Zborowski COMP) Subject: Re: Linux swapping Date: 29 May 1992 11:19:35 GMT
csg203@cch.coventry.ac.uk (Bluebeard) writes:
>
>I have 2megs of memory and 4megs of swap.
>
>Does this give me a total of 6megs or only 4 ?
>
>A unix expert, told me that the actual memory maps onto the swap, so only the
>swap space above the system memory is available.
>Is this true on linux ?
>
>I'm considering upgrading to 4meg of RAM, but as I've only got a 40meg
>partition, I wasn't intending to increase the swap space.
>
>
>Thanks for any info on the above.
>
>
>--
>***********************************************************************
>* FLESH: Charlie Freckleton * JANET: csg203@uk.ac.cov.cck *
>* ALIAS: Bluebeard * or : stliaise@uk.ac.cov.cck *
>***********************************************************************
this is not true under linux. under bsd systems there are two memory
management schemes used which use the disk: swapping and paging. paging
is what linux uses: when there is no physical memory for a page, one
is evicted to the disk (our swap space) to make room. swapping is the
wholesale motion of a process to disk, and is done by the swapper process.
if your process doesn't do anything for a while the system decides its
better to hedge it bets and evict the whole thing to disk, betting on
locality of reference on a process granularity, i guess.
linux simply does paging, using as much swap as is available. if there
isn't any available, the program waits. linus, correct me if i'm wrong,
but this is what i remember when i hacked with it.
zorst
[obz@raster.kodak.com]
-- zorst (orest zborowski) [obz@raster.Kodak.COM]