Re: shared pagetable benchmarking

On Fri, Dec 20, 2002 at 03:11:09AM -0800, Andrew Morton wrote:

Did a bit of timing and profiling.  It's a uniprocessor
kernel, 7G, PAE.
The workload is application and removal of ~80 patches using
my patch scripts.  Tons and tons of forks from bash.
2.5 ends up being 13% slower than 2.4, after disabling highpte
to make it fair.  3%-odd of this is HZ=1000.  So say 10%.
Pagetable sharing actually slowed this test down by several
percent overall.  Which is unfortunate, because the main
thing which Linus likes about shared pagetables is that it
"speeds up forks".
Is there anything we can do to fix all of this up a bit?

For testing purposes, try removing the opportunistic mmap()-time
sharing.


Bill
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