Subject: Re: emulation speeds?
To: None <current-users@NetBSD.ORG>
From: Frank van der Linden <>
List: current-users
Date: 08/17/1995 11:31:08
Quoting Robert Dobbs,

> I run some emulated binaries (BSDI and Linux), but nothing that is
> really hefty.  What sort of cost is involved in running these?  
> Do they run very close to native system speed?

For Linux binaries, there are 2 issues:
    1. Loading the binary might take longer, because the Linux shared libs
       may have to be loaded (if this is the first Linux binary you run). For
       NetBSD binaries you won't really notice this, because the shared
       libs have been mapped sometime during system startup when the first
       shared binary was run. Also some Linux binaries can't be demand paged
    2. There is a little overhead in some system calls, some structure
       conversions and copyin/copyout going on. However, this doesn't affect
       some of the heavily used system calls, like read(2) or write(2).

For BSDI binaries, point 2 does not apply. I am not sure if they have
shared libraries yet (does 2.0 have them?).

All in all, the overhead should be minimal with Linux binaries, and can
be neglected with BSDI binaries.

- Frank