Re: RELENG_4 -> 5 -> 6: significant performance regression


Hello!

On Fri, 12 May 2006, Kris Kennaway wrote:
%Sys %Intr %Idl
RELENG_6 + rl0 45 40 15
RELENG_6 + fxp0 45 35 20

%Sys %Intr %Idl "time md5 -t" wall clock time
RELENG_6 + rl0 34 24 42 1:43
RELENG_6 + fxp0 30 20 50 1:40

is caused by just these:

options INVARIANTS
options INVARIANT_SUPPORT

So what is the overall status? I am not clear what your results are.

Results for RELENG_6+rl0 are

%Sys %Intr %Idl
34 24 42

without INVARIANTS, and

%Sys %Intr %Idl
45 40 15

with them. Other options like QUOTA and "makeoptions
CONF_CFLAGS=-fno-builtin" make almost no difference. So, under my test
conditions, the best % of idle CPU time under RELENG_6 is 42%, while under RELENG_4 we had

%Sys %Intr %Idl
14 14 72

under the same conditions (and with INVARIANTS!) ;(

available for application under RELENG_5/6 than under RELENG_4 (under
identical load pattern). I ran "time md5 -t" several (3-5 times) just to
confirm my assumptions, and results didn't vary more than 3%. So I suppose
that ministat isn't necessary in my tests.

Perhaps not when the difference is large, but you need to be very
careful when differences are below ~10%, because it's easy to make
incorrect conclusions.

I agree with you. I would make more measurements if my aim was to determine
which branch between RELENG_5 and _6 to use. But as these results are close
enough, and RELENG_6 is superiour regarding new features (and often stability), IMHO there's no point in using RELENG_5 at all. I'm just trying
to understand why performance of RELENG_6 is worse than in RELENG_4 _that much_, and whether this sad situation can be improved somehow.

Kris

Sincerely, Dmitry
--
Atlantis ISP, System Administrator
e-mail: dmitry@xxxxxxxxxxxxxx
nic-hdl: LYNX-RIPE
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