Re: What to expect with the 2.6 VM

Andrea Arcangeli
2003-07-01T09:27:58Z

On Tue, Jul 01, 2003 at 01:59:39AM -0700, William Lee Irwin III wrote:
> After observing that, the benchmark is flawed because
> (a) it doesn't run long enough to produce stable numbers
> (b) the results are apparently measured with gettimeofday(), which is
> wildly inaccurate for such short-lived phenomena
> (c) large differences in performance appear to come about as a result
> of differing versions of common programs (i.e. gcc)

not enough time right now to answer the whole email which is growing and
growing in size ;), but I wanted to add a quick comment on this. many
shell loads happens to do something similar, and the speed of
compilation will be a very important factor until you rewrite make and
gcc not to exit and to compile multiple files from a single invocation.

The fact is that this is not a flawed benchmark, this is a real life
workload that you can't avoid to deal with, and I want my kernel to run
the fastest on the most common apps I run. I don't mind if swapping is
slightly slower, I simply don't swap all the time for the whole system
time, while I tend to keep the cpu 100% busy always. Still I want the
best possible swapping that is zerocost for me on the other side. Giving
me a CONFIG_SLOWSWAP_FAST_GCC would be more than enough to make me
happy. I don't think I'll resist to the rmap slowdown while migrating to
2.6 if it keeps showing up in the profiling. Especially Martin's number
were not good.

Andrea