Re: 2.1.89 broken?

Scott Lampert (fortunato@heavymetal.org)
Tue, 10 Mar 1998 19:25:16 -0500 (EST)


On 10-Mar-98 Rik van Riel wrote:
> On 10 Mar 1998, Trond Eivind =?ISO-8859-1?Q?Glomsr=F8d?= wrote:
>> Scott Lampert <fortunato@heavymetal.org> writes:
>> > It works for me on my 233MMX, however it seems to be far
>> > less efficient than prior kernels when it comes to memory handling.
>> > It doesn't seem to want to give up much memory from the disk cache,
>> > prefering to stick stuff in swap first.
>>
>> That is my experience as well... I've got 80 MB. It was happy with
>> about 56 MB for caches, 4 MB free and a little less than 20 MB
>> used. Oh - and 75 MB used swap.
>
> You both seem to be ignoring the fact that sticking
> unused stuff in swap is better than freeing disk
> cache pages. In 2.1.89 we age disk cache pages in
> much the same way we age private (in-swap) pages.
> Because the aging is the same, you can be quite sure
> that Linux is doing the right thing...
>
> (and I haven't heard you about worse performance either)

Well the perceived performance sure isn't even remotely close to
prior kernels. As was mentioned in some earlier messages in this thread,
the system completely freezes while transfering stuff to swap, and since
the kernel seems to transfer much more to swap now, it just exacerbates
the problem.
Far be it from me to criticize ideas made by those who know
much more than me, but personally I don't see how transfering stuff to swap
immediately instead of grabbing what ram we can from the disk
cache first could be considered faster or preferable. As far as
I can see, it would be much better performance-wise to delay swapping as
long as there's ram to be had from the disk cache. Isn't this the main
reason the disk cache is dynamic in size?
-Scott

---
Scott Lampert              | Home Page: http://www.heavymetal.org
<fortunato@heavymetal.org> | PGP Key: finger fortunato@heavymetal.org
"Black holes are where God +-----------------------------------------
   divided by zero."

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