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Scsipi guru needed...


I have been trying to find out why the performance of the ciss controller (Compaq raid) in
DL38x is really bad, but as I don't understand anything about the scsipi
layer (are there any docs?) I must ask around.  All this is really strange.

Writing data to the raw sd device (bs=64k) gets just over 7MB/s, which is quite slow.
Some debugging showed that:
- A write transfer (from given to the ctlr to interrupt) takes 8ms. Ok, no write cache on the ctlr maybe? - Only one (1) active transfer at a time, even though the ctlr can have 1024.

Looking in sdstart it seems that periph_openings is 1, which means only one at a time. Increasing it to 40 (using ddb) makes the machine a little faster, but not much.

The config stuff in ciss.c to setup this seems correct to me, but someone that understands it may have some ideas...? It should be noted that FreeBSD works very well with this controller, while NetBSD doesn't :-/

Hints please?

-- Ragge

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