On Thu, 13 Nov 2008, Linus Torvalds wrote:
Before:
[torvalds@nehalem linux]$ /usr/bin/time git diff > /dev/null
0.03user 0.04system 0:00.07elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k
After:
0.02user 0.07system 0:00.04elapsed 243%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+2241minor)pagefaults 0swaps
ie it actually did cut elapsed time from 7 hundredths of a second to just
4. And the CPU usage went from 100% to 243%. Ooooh. Magic.
But it's still hacky as hell. Who has NFS? Can you do the same thing over
NFS and test it? I'm not going to set up NFS to test this, and as I
suspected, on a local disk, the cold-cache case makes no difference
what-so-ever, because whatever seek optimizations can be done are still
totally irrelevant.
The timings seem to vary quite a bit (not really a surprise with a network
involved ;), but the patch definately makes things faster:
master:
jp3@kaos: linux-2.6(master)>/usr/bin/time ~/bin/git diff > /dev/null
0.01user 0.19system 0:02.50elapsed 8%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+1766minor)pagefaults 0swaps
master + patch:
jp3@kaos: linux-2.6(master)>/usr/bin/time ~/bin/git diff > /dev/null
0.02user 0.88system 0:00.96elapsed 93%CPU (0avgtext+0avgdata
0maxresident)k
0inputs+0outputs (0major+1783minor)pagefaults 0swaps
seems to be approximately twice as fast?
--
Julian
---
<nelchael> "XML is like violence, if it doesn't solve the problem, just
use more."
* nelchael hides
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