cache and buffer usage with kernel 2.6.10

cache and buffer usage with kernel 2.6.10

[M Benz]

Hello,

I just upgrade my linux box from 2.6.8.1 to 2.6.10 yesterday, and I found 
that the memory usage behavier is very different btw the 2 kernels. I built 
2.6.10 with the same .config with my 2.6.8.1

My box is a Pentium 4 HT machine, with 2GB of RAM, it's running apache to 
service a very busy website, around 1.5M PHP pageviews per day.

With kernel 2.6.8.1, "top" always show me acount 150MB buffer, 1.3-1.5GB 
cached, and 1-2M free, after switch to  kernel 2.6.10, "top" shows me 
around 500MB buffer, 800M cache, and several MB free. after around 10 hours 
with 2.6.10, top now shows me 800MB buffer, 500MB cache and 2-300MB free.

Is there any change with memory management btw the two kernels? Also, what 
is the different btw "cache" and "buffer"? Why don't kernel 2.6.10 use all 
the memory but leave around 200MB free?

Thanks.

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Re: cache and buffer usage with kernel 2.6.10

[Ingo Oeser]

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On Monday 27 December 2004 17:33, M Benz wrote:
> Is there any change with memory management btw the two kernels? Also, what 
> is the different btw "cache" and "buffer"? Why don't kernel 2.6.10 use all 
> the memory but leave around 200MB free?

These metrics have been useless from the very beginning and are
not very descriptive. If you like to get some meaning in
your statistice, use vmstat. This is more costly, but actually shows
something about the performance of your system.

Maybe we could concentrate on exporting these metrics instead buffer/cache
and provide dummy metrics for them. At least "buffer" can be made to
sth. like "shared" does now.

Regards

Ingo Oeser


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