Suggestions on Avoiding syscall Overhead
kris at obsecurity.org
Tue Apr 24 04:53:56 UTC 2007
On Mon, Apr 23, 2007 at 09:05:51PM -0700, Tim Kientzle wrote:
> >>>>We can have 3 type of pages mapped into one process's address map.
> >>>>1. System wide global readonly page which will help on these syscalls:
> >>>>2. Per process Readonly page. (change will still through standard
> >>>>help on the syscalls:
> >>>>getuid, geteuid, getpid,getgid, getegid, getpgrp,
> >>I don't really understand this suggestion.
> >>Do any real programs call these syscalls very often?
> >There is indeed more and more programs calling some syscalls a
> >*lot* .... MySQL calls gettimeofday() so much that changing
> >the timer used on a system can lead to a very observable performance
> >improvement. Similarly, PostgreSQL calls setproctitle() a lot ...
> Accelerating gettimeofday() makes a lot of sense; I've seen a
> lot of programs that call it very often.
> I'm not convinced about calls such as getuid() and gethostname(),
> though. Putting this kind of information in userspace
> introduces forward-compatibility concerns. People do
> statically link against libc, so you have to make sure that libc can
> find this information even when running on future kernels.
> That makes each such call a tricky maintenance issue.
Well you will have to keep compatibility syscalls anyway, because not
everything even links to libc ;)
More information about the freebsd-current