Re: softirqd

From: Peter Chubb
Date: Tue Nov 18 2003 - 17:26:29 EST





Kernwek Jalsl said:

Kernwek> Sorry in case I was not very clear with my
Kernwek> requirements. With real time interrupt I meant a
Kernwek> real time task waiting for IO from this interrupt.
Kernwek> Assume that I have a high priority interrupt and a
Kernwek> real time task waiting for it. Well followimg are the
Kernwek> various latencies involved:
Kernwek> L1- interrupt latency
Kernwek> L2- hard and soft IRQ completion
Kernwek> L3 - scheduler latency
Kernwek> L4 - scheduler completion

Kernwek> L1 is pretty acceptable on Linux.

I've been trying to measure this. On IA64 I'm measuring around
2.5microseconds (on a 900MHz machine). I personally think that this
is too big, and could be reduced.

One thing I think we need to do early in 2.7 is to merge all those
architecture-dependent arch/XXX/kernel/irq.c files, and try to reduce
the amount of duplicated work done in the new merged file and the
lower level architecture-specific files.

--
Dr Peter Chubb http://www.gelato.unsw.edu.au peterc AT gelato.unsw.edu.au
The technical we do immediately, the political takes *forever*

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