Re: [PATCH] get_nodes mask miscalculation
From: Andi Kleen (ak_at_muc.de)
Date: 08/10/04
- Previous message: Jens Axboe: "Re: PATCH: cdrecord: avoiding scsi device numbering for ide devices"
- In reply to: Brent Casavant: "Re: [PATCH] get_nodes mask miscalculation"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Date: 10 Aug 2004 17:34:56 +0200 Date: Tue, 10 Aug 2004 17:34:56 +0200 To: Brent Casavant <bcasavan@sgi.com>
On Tue, Aug 10, 2004 at 09:54:08AM -0500, Brent Casavant wrote:
> On Tue, 10 Aug 2004, Andi Kleen wrote:
>
> > The idea behind this is was to make it behave like select.
> > And select passes highest valid value + 1.
>
> Not that my opinion is worth much, but this seems a very peculiar
> interface to mimic.
It is the only system call I am aware of that passes a variable
length bitmap. Do you know of any others?
> > nodemask."
>
> Actually, I worked from the following description:
>
> mbind(3)
> . . .
> nodemask is a bit field of nodes that contains up to
> maxnode bits.
> . . .
>
> This very clearly indicates that I should pass the number of bits
> in the nodemask field, not the number of bits plus one.
I really need to rewrite the mbind manpage - it was a quick
hack job and has several other errors.
> > Problem is that you'll break all existing libnuma binaries
> > which pass NUMA_MAX_NODES + 1. In your scheme the kernel
> > will access one bit beyond the bitmap that got passed,
> > and depending on its random value you may get a failure or not.
>
> Well, again, not that my opinion carries much weight (nor really should
> it), but this whole off-by-one (or two) interface seems unnecessarily
> confusing. Is there no way we can get this fixed? The temporary pain
Sure, new system call slots would do with a small compat wrapper
for the old calls. I'm just not sure it is worth it. I personally
don't find it that confusing, but I'm probably not a good benchmark
for this.
> of breaking the relatively new libnuma seems worth the price of getting
> this forever cleaned up.
I don't think breaking existing binaries is a good idea. Linux
has higher standards.
-Andi
-
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/
- Previous message: Jens Axboe: "Re: PATCH: cdrecord: avoiding scsi device numbering for ide devices"
- In reply to: Brent Casavant: "Re: [PATCH] get_nodes mask miscalculation"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Relevant Pages
|
