2.2.15pre5, IDE and Athlon problem(s)

From: Gabriele Turchi (turchi@tieffesistemi.com)
Date: Sat Feb 05 2000 - 17:47:22 EST


Hi all.

We are testing an Athlon system with the following configuration:

MB MS-6167, Athlon 650, 128 MB RAM, 2 Quantum Fireball KX 27.3GB 7200rpm,
ethernet D-Link 100Mbps DFE-538TX. Linux kernel is a 2.2.15pre5 with
ide.2.2.15-5.20000127 and latest raid beta from RedHat. UDMA on disks
is active.

Our feeling on overall performances is: STUNNING! But we're experiencing
a slowdown in interactive performances during high disk activity.

Apparently, especially under X, the system swaps-out pages "aggressively"
to allocate more and more buffer-cache.

One test which freeze almost completely the system is:

dd if=/dev/zero of=/home/1 bs=1024k &

/home is a 20GB raid1 (mirrored) filesystem (dd is stopping at 2GB file limit).

A similar 2.2.15pre1-based kernel gave same result. Again on a 2.2.12-20
plain RedHat 6.1 kernel. The same test on a similar host on a not-raid disk
gave the same result.

Is a vm-subsystem problem (too many cache allocated)? Is a IDE subsystem
problem (too large queues, especially in writing)?

The system is not in production (yet), so we can run other tests or benchmarks
needed/requested to better diagnose the problem.

Please cc to me, since I'm not subscribed.

Best wishes,

        Gabriele Turchi

-- 
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 Gabriele Turchi (Responsabile Tecnico)            turchi@tieffesistemi.com
 Tieffe Sistemi S.r.l.                                www.tieffesistemi.com
 V.le Piceno 21 - 20129 Milano - Italia             tel/fax +39 02 76115215
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