Re: [linux-usb-devel] Re: [PATCH 00/10] usb-serial: Switches fromspin lock to atomic_t.

[Arjan van de Ven]

On Wed, 2005-12-07 at 16:37 +0100, Oliver Neukum wrote:
> Am Mittwoch, 7. Dezember 2005 16:22 schrieb Arjan van de Ven:
> > > On the other hand, Oliver needs to be careful about claiming too much.  In 
> > > general atomic_t operations _are_ superior to the spinlock approach.
> > 
> > No they're not. Both are just about equally expensive cpu wise,
> > sometimes the atomic_t ones are a bit more expensive (like on parisc
> > architecture). But on x86 in either case it's a locked cycle, which is
> > just expensive no matter which side you flip the coin...
> 
> You are refering to SMP, aren't you?

yes.
on UP neither is a locked instruction ;)

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