Re: [PATCH] lazy freeing of memory through MADV_FREE

Rik van Riel
2007-04-23T11:46:15Z

Rik van Riel wrote:

> First some ebizzy runs...

This is interesting. Ginormous speedups in ebizzy[1] on my quad core
test system. The following numbers are the average of 10 runs, since
ebizzy shows some variability.

You can see a big influence from the tlb batching and from Nick's
madv_sem patch. The reduction in system time from 100 seconds to
3 seconds is way more than I had expected, but I'm not complaining.
The 4 fold reduction in wall clock time is a nice bonus.

According to Val, ebizzy shows the weaknesses of Linux with a real
workload, so this could be a useful result.

kernel
user system wall clock %CPU

vanilla 186s 101s 123s 230%
madv_free (madv) 175s 96s 120s 230%
mmap_sem (sem) 100s 40s 40s 370%
madv+sem 200s 140s 100s 393%
madv+sem+tlb 118s 3s 30s 395%
madv+tlb 150s 10s 50s 310%

[1] http://www.ussg.iu.edu/hypermail/linux/kernel/0604.2/1699.html
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