Re: HZ and real-time performance

Sven Heursch (Sven.Heursch@unibw-muenchen.de)
Sat, 03 Jul 1999 02:21:04 +0200


nunca wrote:

> I've been playing with writing real-time guitar effects boxes, and I've
> gotten the latency down to 11ms with stock linux. Would changing the HZ
> constant to 1024 help me reduce the latency (ie, does it cause a task to
> get scheduled more often)? Any other/better suggestions for decreasing
> latency? Thanks in advance.
> -Nolan
>
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for POSIX 4 (today better: IEEE 1003.1b Real time & I/O) you should read
this document:

ftp://ftp.informatik.uni-erlangen.de/local/cip/mskuhn/misc/linux-posix.1b

because this document is not very new, there are a few changes in the linux
kernel and the glibc 2.1.

New are for example the "_POSIX_REALTIME_SIGNALS". But for the newest
possiblities you should look into the sources of the glibc or the kernel
header files! (unistd.h etc.)

Very interesting is the fact that a few features cannot be implementet.
e.g.
the POSIX function pthread_attr_setscope(), because of the "one-to-one"
model of linux threads.

greetings

S.Heursch

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