Re: [Lse-tech] Re: RFC: patch to allow lock-free traversal of lists with insertion

Victor Yodaiken
2001-10-10T15:28:18Z

On Wed, Oct 10, 2001 at 11:31:08AM +0530, BALBIR SINGH wrote:
> Linus Torvalds wrote:
> >I can't think of many lists like that. The PCI lists certainly are both
> >add/remove: cardbus bridges and hotplug-PCI means that they are not just
> >purely "enumerate at bootup".
> >
>
> I agree, I just thought of one case quickly. Assume that somebody did a cat /proc/pci.
> Meanwhile somebody is adding a new pci device (hotplug PCI) simultaneously (which is very rare).
> I would not care if the new device showed up in the output of /proc/pci this time. It would
> definitely show up next time. Meanwhile locking the list (just in case it changes) is an
> overhead in the case above. I was referring to these cases in my earlier mail.

So you make the data structure and algorithms more complex and hard to maintain in
order to get an undetectable improvement in the speed of something that almost
never happens and and that is not even in the same neighborhood as being a
bottleneck?