[nylug-talk] LOWMEM vs. HIGHMEM performance advantage?

[Peter C. Norton]

On Thu, Apr 17, 2008 at 10:30:55AM -0400, jh wrote:
> I have an application that appears to slow down once it starts using 
> about 900 megs of memory.
> 
> Interestingly, from dmesg:
> 
> [42949372.960000] 1150MB HIGHMEM available.
> [42949372.960000] 896MB LOWMEM available.
> 
> Is HIGHMEM slower, or are there circumstances or kernel configs such 
> that I could be seeing such a slowdown once memory usage goes above a 
> certain level?

Are you using a 2.4 kernel? I thought the split was moved much closer
to the 4gb line in 2.6.

http://www.linux.org/docs/ldp/howto/IO-Perf-HOWTO/overview.html

-Peter


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