Re: [BENCHMARK] 2.4.{18,19{-ck9},20rc1{-aa1}} with contest

From: Andrea Arcangeli (andrea@suse.de)
Date: Sun Nov 10 2002 - 11:27:06 EST


On Sun, Nov 10, 2002 at 11:12:47AM +0100, Kjartan Maraas wrote:
> lÝr, 2002-11-09 kl. 14:54 skrev Jens Axboe:
>
> [SNIP]
>
> > The default is 2048. How long does the io_load test take, or rather how
>
> The default on my RH system with the latest errata kernel is as follows:
>
> [root@sevilla kmaraas]# elvtune /dev/hda
>
> /dev/hda elevator ID 0
> read_latency: 8192
> write_latency: 16384
> max_bomb_segments: 6

that has still the bugs in 2.4.19 and all previous 2.4 that I found and
that I fixed first with an limited patch, not complete, and then Jens
fixed it competely after I showed him the bugs while explaining him why
I did the first limited patch (then Jens's patch gone in 2.4.20pre).

so a 8192 there, isn't comparable to a 8192 in 2.4.20rc, Jens was of
course aware and just lowered it to 2048 but that is probably still more
than a 8192 in previous 2.4, it would be possible to do the math to
calculate the exact value in some common case but I guess we want a sane
default, not necessairly the exact same behaviour, so I guess
benchmarking is more useful than doing the math to calculate the exact
new value to get the exact same behaviour.

Andrea
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