Message-ID: <20010224143354.15276.qmail@web1302.mail.yahoo.com>
Date: Sat, 24 Feb 2001 06:33:54 -0800 (PST)
From: Mark Swanson <swansma@yahoo.com>
Subject: 2.4.2-ac3 == 400% speed improvement with Java
To: linux-kernel@vger.kernel.org
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Sender: linux-kernel-owner@vger.kernel.org

Hello,

any 2.4.1-ac5 kernel and above until 2.4.2-ac3 had a bug (Ingo guessed
it might be the yield() bug) that made Java (and some other things
*really* slow). This is fixed now. When I profiled slow kernels the
mtrr_file_add was taking up all of the time - even though I had
disabled mtrr in my kernel (it wasn't in /proc).

(Alan Cox: I'm not sure if the yield() bug was the problem, or if that
patch was in the TUX patch (based on -ac3) or the -ac3 patch.)

Here was the old test: (With 2.4.2-ac3 things are even faster than
2.2.14 at 0:00.44elapsed!!)

(jdk1.3.0_01)
> time java
(done multiple times so everything is in cache)

On 2.2.14 (400MHz Celeron/192MB RAM) this takes about 0.66ms.
0.37 user 0.07 system  0:00.62elapsed 70% CPU (oavgtext+0avgdata
0maxresident)k
0inputs+0outputs (3957major+1707minor)pagefulats 0swaps

On linux 2.4.2-ac1-TUX (same machine)

0.33 user 2.17 system 0:03.49elapsed 71%CPU (ovgtext+0avgdata
0maxresident)k
0inputs+0outputs (3987major+1784minor)pagefaults 0swaps


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