RELENG_4 -> 5 -> 6: significant performance regression

[Jonathan Noack]

On 05/13/06 01:59, Dmitry Pryanishnikov wrote:
> 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.

Have you tried putting I586_CPU in there?  See
http://lists.freebsd.org/pipermail/freebsd-stable/2005-December/020696.html.

Also, use the link0 option with your fxp cards if they support it.  See
the fxp(4) man page for more info.  Here is an example /etc/rc.conf entry:
ifconfig_fxp0="inet xxx.xxx.xxx.xxx netmask xxx.xxx.xxx.xxx link0"

-- 
Jonathan Noack | noackjr at alumni.rice.edu | OpenPGP: 0x991D8195

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