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Re: Mach lack for frequent operations

From: Gianluca Guida
Subject: Re: Mach lack for frequent operations
Date: Thu, 1 Dec 2005 18:41:05 +0000

On 12/1/05, ams@gnu.org <ams@gnu.org> wrote:
> To get an idea how hard fork() is for us, Gianluca did a simple test,
> on GNU/Hurd he got 312 forks/second, and on the same machine but in
> GNU/Linux, he got 8170 forks/second.

FYI, I just compiled and executed under linux and under hurd the forks
benchmark code provided with hurd (in benchmark/forks.c).

Results were very 'stable' in Hurd and the forks per second rate was
incredibly constant.

I made the test for benchmarking the improvements that GNU Mach could
have by supporting the PGE bit functionality available in Pentium and
later processors: basically you set Kernel's page table entries as
'global' thus they are not invalidated during a context switch; this
lead to an often noticeable improvement in context switching
performance, but in the GNU Mach + GNU Hurd case, the overall system
improvement was a crappy +3% in the forks test.


It was a type of people I did not know, I found them very strange and
they did not inspire confidence at all. Later I learned that I had been
introduced to electronic engineers.
                                                  E. W. Dijkstra

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