Re: Protecting global lookup array

[Mindaugas Rasiukevicius <rmind%netbsd.org@localhost>]

Masao Uebayashi <uebayasi%tombi.co.jp@localhost> wrote:
> I'm adding another list of vm_physseg for device pages.  It's a list or
> array of physical address segments.  They're frequently accessed by VM to
> lookup a physical address from a page metadata (vm_page) or vice versa.
> 
> Those lists are rarely updated.  When a framebuffer or memory-mappable audio
> device are attached / detached.  (For RAM segments, they're updated when
> we'll support memory hot-plug. :)
> 
> The update process is very rare, and expected.  Administrators carefully
> connects a device when the machine is not running some important task.  So
> what I need here is to protect such a data adding no run-time performance
> loss.
> 
> Do we have any standard way to do this?

Passive serialization (i.e. RCU-like approach) should fit here.

-- 
Mindaugas