Date: Mon, 29 Jan 2001 09:37:32 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: "Jacques A. Vidrine" <n@nectar.com> Cc: mouss <usebsd@free.fr>, Garance A Drosihn <drosih@rpi.edu>, Luigi Rizzo <rizzo@aciri.org>, hackers@FreeBSD.ORG, wollman@khavrinen.lcs.mit.edu Subject: Re: [kernel patch] fcntl(...) to close many descriptors Message-ID: <200101291737.f0THbWg65163@earth.backplane.com> References: <200101290303.f0T33qg60603@earth.backplane.com> <200101281837.f0SIbGI24332@iguana.aciri.org> <200101290303.f0T33qg60603@earth.backplane.com> <p05010400b69ac2c32903@[128.113.24.47]> <4.3.0.20010129145823.023dfeb0@pop.free.fr> <20010129081455.B2390@hamlet.nectar.com>
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:> As for the "generic" syscall mechanism, I'd love it. I think that
:> there are many places where "names" would be good, instead of
:> hardcoded numbers. The only problem is to find a way to do that
:> without reducing performance. names are good. just try to see what it
:> would be if filenames were replaced by inodes. I think that having a
:> name-based mechanism makes it easier to add new syscalls or reject
:> deprecated ones.
:
:Performance is not much of an issue. A perfect hash can be generated
:for syscall names.
This is a bad idea. One of the reasons why it is so easy for us to
write portability modules for Sun, Linux, etc... is because of the
hard-coded syscall numbers. Syscalls work plenty well enough as they
are now, we do not need a new mechansm.
:> (thanks to svr4 lobbying into posix:).
:> - add a closeall macro to call it.
:>
:> this gives both aix and netbsd compat (and if the fcntl thing goes into
:> netbsd, the compat would be full).
:
:I really do not care for using fcntl with this. fcntl operates on a
:single file descriptor -- F_CLOSEM mucks up the interface.
:
:--
:Jacques Vidrine / n@nectar.com / jvidrine@verio.net / nectar@FreeBSD.org
mmap() is overloaded for MAP_ANON. fcntl() may not be perfect, but
it's better then adding a new syscall.
The libc closeall() code (I'm assuming that Mouss does not intend to
actually use a #define) could do the fcntl(), and if it fails fall
back to close()ing descriptors in a loop. Perfect!
-Matt
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