harddisk speed: 2.4.24 20+% faster then 2.6.3

harddisk speed: 2.4.24 20+% faster then 2.6.3

[Danny ter Haar]

I've been checking, rechecking but cannot explain
why a "vannilla" debian install kernel (sid-testing install
cdrom) is faster then "Feisty Dunnart" on the same hardware.

hardware: Mini-itx with 1Ghz via-C3
200GB udma harddisk.

2.4.24:  
 Timing buffered disk reads:  150 MB in  3.01 seconds =  49.83 MB/sec

2.6.3 (vanilla):
 Timing buffered disk reads:  102 MB in  3.05 seconds =  33.40 MB/sec

2.6.3-mm4:
 Timing buffered disk reads:  108 MB in  3.00 seconds =  35.95 MB/sec

Bonnie tests confirm this!

hdparm & bonnie & kern.log for comparison put at: http://dth.net/c3/

Anyone any idea *why* ?

Mayby i'm overlooking something (it's kind of late on this
side of the pond) but still...

Open for feedback.

Danny

-- 
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Re: harddisk speed: 2.4.24 20+% faster then 2.6.3

[Paul]

Danny ter Haar <dth@ncc1701.cistron.net>, on Fri Feb 27, 2004 [12:04:29 AM] said:
> I've been checking, rechecking but cannot explain
> why a "vannilla" debian install kernel (sid-testing install
> cdrom) is faster then "Feisty Dunnart" on the same hardware.
> 
> hardware: Mini-itx with 1Ghz via-C3
> 200GB udma harddisk.
> 
> 2.4.24:  
>  Timing buffered disk reads:  150 MB in  3.01 seconds =  49.83 MB/sec
> 
> 2.6.3 (vanilla):
>  Timing buffered disk reads:  102 MB in  3.05 seconds =  33.40 MB/sec
> 
> 2.6.3-mm4:
>  Timing buffered disk reads:  108 MB in  3.00 seconds =  35.95 MB/sec
> 

	Hi;

	
	By default, my hdparm numbers and my kernel build time
benchmark were worse on all 2.6 vs. 2.4 kernels, until I tried:

/sbin/hdparm -a 4096 /dev/hdx

eg. (typical averages)
2.4.21:
Timing buffered disk reads:   80 MB in  3.07 seconds =  26.06 MB/sec
2.6.0-test5:
Timing buffered disk reads:   68 MB in  3.06 seconds =  22.21 MB/sec
2.6.1: [readahead 4096]
Timing buffered disk reads:   90 MB in  3.02 seconds =  29.82 MB/sec

2.6.0-test10 building 2.4.18-packet (personal config) gcc3.2.3 glibc2.3.2
160g Maxtor, ext3
(2xpII 400)
time (make -j4 clean && make -j4 dep && make -j4 bzImage)
[with default read-ahead]
real    9m1.496s
user    16m1.977s
sys     0m45.347s

[read-ahead = 4096]
real    7m2.923s
user    12m6.889s
sys     0m46.190s

	pIIx4, ata33, 160g maxtor

Paul
set@pobox.com

Re: harddisk speed: 2.4.24 20+% faster then 2.6.3

[Danny ter Haar]

Paul  <set@pobox.com> wrote:
>By default, my hdparm numbers and my kernel build time
>benchmark were worse on all 2.6 vs. 2.4 kernels, until I tried:
>/sbin/hdparm -a 4096 /dev/hdx
>eg. (typical averages)
>2.4.21:
>Timing buffered disk reads:   80 MB in  3.07 seconds =  26.06 MB/sec
>2.6.0-test5:
>Timing buffered disk reads:   68 MB in  3.06 seconds =  22.21 MB/sec
>2.6.1: [readahead 4096]
>Timing buffered disk reads:   90 MB in  3.02 seconds =  29.82 MB/sec

Allready thought about that, tried that but no real

difference:belfish:~# uname -a
Linux babelfish 2.6.3-mm4 #3 Fri Feb 27 14:09:38 CET 2004 i686 GNU/Linux

babelfish:~# /sbin/hdparm -a 4096 /dev/hda
/dev/hda:
setting fs readahead to 4096
readahead    = 4096 (on)

babelfish:~# hdparm -t /dev/hda
Timing buffered disk reads:  110 MB in  3.02 seconds =  36.47 MB/sec

I just installed a news amd64 en few 19" servers.
But none of them showed downgrade in performance when i upped the
kernel.

Possibilities left (according to me!)

- scheduler (should i try different setup ?)
- irq problems (in combination with acpi?)
  i booted with acpi=off and retested but same results.
- driver, specific the via-onboard.

No luck so far!

Danny
-- 
 /"\                        | Dying is to be avoided because
 \ /  ASCII RIBBON CAMPAIGN | it can ruin your whole career 
  X   against HTML MAIL     | 
 / \  and POSTINGS          | - Bob Hope