Re: Linux slowdown on 20M - summary

Bill Broadhurst (
Fri, 25 Apr 1997 07:28:28 -0700

On Fri, Apr 25, 1997 at 03:11:55PM +0200, Pavel Machek wrote:

[much deleted
> Other think I noticed is that time from Uncompressing kernel to Elf:login differs heavily (15 sec X 25 sec) with 16MB and 20MB
> of memory (16MB is faster). Also 'interactive performance' is much
> worse with 20MB.
> Both even if l2 disabled.
> Other ideas (beside of cache problems were:)
> Problems with disk access not possible to memory higher that 16MB directly -
> impossible since I do not use DMA on disks and since disk activity when
> compiling kernel is almost none.
> David (?) Told me something about inode cache.
> Pavel

It sounds to me like you're running into an interleave problem. Does your chipset
support interleave?

More to the point, how many modules do you have installed in each configuration?
And are the modules all the same size?

Some motherboards will interleave the memory banks as long as the banks are full
and contain the same size DRAM modules. I have a board here that has eight
sockets. If the sockets are filled with it's MUCH faster than
if it contains - same amount of DRAM.
Another board here has two sockets, and runs faster with two eights than with an
16M module.


Might not be your situation but it would explain what you're seeing.


Dr. Bill Broadhurst                  	  Contract Engineer to:            	       	  Doctor Design Inc.
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