Re: Intel P6 vs P7 system call performance

Richard B. Johnson
2002-12-18T13:07:47Z

On Tue, 17 Dec 2002, Linus Torvalds wrote:

>
> On Tue, 17 Dec 2002, Linus Torvalds wrote:
> >
> > How about this diff? It does both the 6-parameter thing _and_ the
> > AT_SYSINFO addition.
>
> The 6-parameter thing is broken. It's clever, but playing games with %ebp
> is not going to work with restarting of the system call - we need to
> restart with the proper %ebp.
>
> I pushed out the AT_SYSINFO stuff, but we're back to the "needs to use
> 'int $0x80' for system calls that take 6 arguments" drawing board.
>
> The only sane way I see to fix the %ebp problem is to actually expand the
> kernel "struct ptregs" to have separate "ebp" and "arg6" fields (so that
> we can re-start with the right ebp, and have arg6 as the right argument on
> the stack). That would work but is not really worth it.
>
> Linus
>

How about for the new interface, a one-parameter arg, i.e., a pointer
to a descriptor (structure)?? For the typical one-argument call, i.e.,
getpid(), it's just one de-reference. The pointer register can be
EAX on Intel, a register normally available in a 'C' call.

Cheers,
Dick Johnson
Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips).
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