Messages in this thread | | | Date | Mon, 3 Aug 1998 13:16:50 -0400 (EDT) | From | Rafael Reilova <> | Subject | Re: kernel compile time comparison (2.0 vs 2.1 with 64MB) |
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Hi all,
On Mon, 3 Aug 1998, Andrew Derrick Balsa wrote:
> Hi Peter, > > On Mon, 03 Aug 1998, Peter T. Breuer wrote: > .... > > > >Kernel compilation seems cpu and/or memory bound, and the measurements > >seem to indicate that the measurements that I make don't distinguish the > >two. > > It's hard to tell unless you keep the other parameter constant, and in the case > of the Celeron oc.@412MHz vs. PPro200, this is impossible. The Celeron has a > small 32KB L1 cache and that's it. The PPro has both an L1 cache and an L2 > cache (you didn't say but I assume it is the more common 256KB model).
Not having a L2 cache is a killer to performance. The Celeron is memory bound in this particular case. GCC uses a lot of memory which, of course, doesn't fit on the Celeron L1 cache. What we are probably seeing here are pipeline stalls due to cache misses. These bring a 412Mhz CPU down to a PPro 200 level. Assuming very similar arch, the Celeron is internaly idle 50% of the time (probably more, since PPro isn't 100% busy). Of course, rating CPU performace based on Mhz is a well known fallacy.
Cheers,
Rafael
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