system call overheads

Robert Fish (ssrrfish@rdg.ac.uk)
Thu, 14 Jan 1999 09:26:10 +0000 (GMT)

I am trying to time various stages of system call execution. Over a
million iterations it appears to take 2 microseconds for a Pentium75 to
start executing the nominated handling function. A Pentium II 300 is
slightly faster at 1 microsecond, but both seem slow compared to
other (older Sparc based) architectures.

I have scoured the web trying to find out what happens in the
time between an application issuing the "int 0x80" instruction and the
execution of the system call handler (system_call in
/usr/src/linux/arch/i386/kernel/entry.S).

What happens before the kernel side (system_call) handler gets called ???
Using RH5.1 kernel version 2.1.119.

Many thanks, all replys greatfully received,
Rob.

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