Re: Intel P6 vs P7 system call performance

From: Linus Torvalds (torvalds@transmeta.com)
Date: Thu Dec 19 2002 - 14:37:06 EST


On Thu, 19 Dec 2002 bart@etpmod.phys.tue.nl wrote:
>
> True, but unless I really don't get it, compatibility of a new static
> binary with an old kernel is going to break anyway.

NO.

The current code in 2.5.x is perfectly able to be 100% compatible with
binaries even on old kernels. This whole discussion is _totally_
pointless. I solved all the glibc problems early on, and Uli is already
happy with the interfaces, and they work fine for old kernels that don't
have a clue about the new system call interfaces.

WITHOUT any new magic system calls.

WITHOUT any stupid SIGSEGV tricks.

WITHOUT and silly mmap()'s on magic files.

> My point was that the double-mapped page trick adds no overhead in the
> case of a static binary, and just one extra mmap in case of a shared
> binary.

For _zero_ gain. The jump to the library address has to be indirect
anyway, and glibc has several places to put the information without any
mmap's or anything like that.

                Linus

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/



This archive was generated by hypermail 2b29 : Mon Dec 23 2002 - 22:00:24 EST