lkml.org 
[lkml]   [2002]   [Jan]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: 2.5.2-pre performance degradation on an old 486 (it's the scheduler)
On Sat, 5 Jan 2002 09:25:48 +0100 (CET), Matthias Hanisch wrote:
>On Sat, 5 Jan 2002, Mikael Pettersson wrote:
>
>> When running 2.5.2-pre7 on my old for-testing-only 486(*),
>> file-system accesses seem to come in distinct bursts preceded
>> by lengthy pauses. Overall performance is down quite significantly
>> compared to 2.4.18pre1 and 2.2.20pre2. To measure it I ran two
>> simple tests:
>>
>> Test 1: time to boot the kernel, from hitting enter at the LILO
>> prompt to getting a login prompt
>> Test 2: time to "rm -rf" a clean linux-2.4.17 source tree, using
>> the newly booted kernel (no other access to the tree before that,
>> so it wasn't cached in any way, and the machine was otherwise idle)
>>
>> Test 1 Test 2
>> 2.2.21pre2: 71 sec 75 sec
>> 2.4.18pre1: 64 sec 72 sec
>> 2.5.2-pre7: 97 sec 251 sec
>>
>> I haven't noticed any slowdowns on my other boxes, so I didn't
>> do any measurements on them. On the 486 it's very very obvious.
>
>This is exactly, what I see with my old 486 box. It started with
>2.5.2-pre3, which contained two major items:
>
>- bio changes from Jens
>- scheduler changes from Davide
>
>Surprisingly, backing out the bio changes didn't help. Backing out the
>scheduler changes from Davide did!!

BINGO! Running 2.5.2-pre8 with the scheduler changes backed out made
all the difference! Interactive responsiveness is much improved and
performance in the above two tests I ran is back to 2.4.18pre1 levels.

With 2.5.2-pre8 vanilla the 486 is getting large variation in Test 2
above (157s, 237s, 292s), but is never even close to 2.2/2.4 levels.

>> (*) 100MHz 486DX4, 28MB ram, no L2 cache, two old and slow IDE disks,
>> small custom no-nonsense RedHat 7.2, kernels compiled with gcc 2.95.3.

/Mikael
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:15    [W:0.053 / U:2.248 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site