[ltp] Thinkpad T43 cached read Speed(hdparm -T) mystery

[Michael Karcher]

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Am Mittwoch, den 25.06.2008, 14:05 -0400 schrieb
jqian@physics.harvard.edu:
[...]
> Thanks so much for this really detailed explanation! Though I don't=20
> understand everything you said, it really helps!
>=20
> I guess from what I understand, I can recover the old performance by=20
> recompiling the kernel myself.
I guess so. I didn't try myself, but it seems very probable.

> If, as I understand from what you said, the performance gain from day=20
> to day computing is small, I would rather forgo this recompilation for=20
> now,
You got it right. At best I would estimate you can get at best a 3%
performance gain in day-to-day-computing for tasks that do lot of big
read() calls. A rule of thumb is, that performance gains below 30% a
hardly noticable. So just let it as it is now.

>  let along recompilation of libc.
I never even wanted to recommend that to you, I just wanted to point out
that the kernel memory copy performance does even less to your system
performance than you might expect, as userspace programs use libc
instead.

As you run a 32 bit system, you might want to install libc6-i686 (if it
is not already installed) to obtain better performance than libc6 would
deliver.

>  As a bumper sticker in  Silicon=20
> Valley allegedly said, "life is too short to compile Gentoo"!(No=20
> offense to gentoo users).
Compiling gentoo is a hobby, IMHO, but not the right approach if you
want to use the computer for your work *now*.

Regards,
  Michael Karcher

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