Re: [uml-devel] [PATCH] host context switch reduction

[Nuno Silva <nuno.silva@vgertech.com>]

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Laurent Vivier wrote:

[..]

| netserver:/usr/src# uname -a
| Linux netserver 2.4.24-sysemu #4 SMP Tue Feb 17 16:43:11 CET 2004 i686
GNU/Linux
|
| netserver:/usr/src# time ./getpid 1000000
|
| real    0m1.763s
| user    0m0.910s

Just want to comment on this.

Benchmarks of syscall performance on systems with TLS and recent glibc
should not use getpid()... I don't know why, but on my system getpid
alone is *very* fast.

(This is wrt the host. UML doesn't do TLS yet)

To benchmark simple syscalls you may get "real" (in the sense that you
can compare the result values to UML/host systems) values with something
like this:

int main()
{
~ long counter=0;
~ int a;
~ while( counter < 10000000)
~ {
~  counter++;
~  a=getppid();
~  a=getgid();
~ }
}

Regards,
Nuno Silva


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