Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation | From | Arjan van de Ven <> | Date | Fri, 22 Apr 2005 20:12:58 +0200 |
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On Fri, 2005-04-22 at 12:55 -0500, Timur Tabi wrote: > Arjan van de Ven wrote: > > On Mon, 2005-04-18 at 11:09 -0500, Timur Tabi wrote: > > > >>Roland Dreier wrote: > >> > >>> Troy> How is memory pinning handled? (I haven't had time to read > >>> Troy> all the code, so please excuse my ignorance of something > >>> Troy> obvious). > >>> > >>>The userspace library calls mlock() and then the kernel does > >>>get_user_pages(). > >> > >>Why do you call mlock() and get_user_pages()? In our code, we only call mlock(), and the > >>memory is pinned. > > > > > > this is a myth; linux is free to move the page about in physical memory > > even if it's mlock()ed!! > > Can you tell me when Linux actually does this? I know in theory it can happen, but I've > never seen it. Does the code to implement moving of data from one physical page to > another even exist in any version of Linux?
hot(un)plug memory.
> > Also, what would be the point? What reason would there be to move some data from one > physical page to another, while keeping the same virtual address?
so that you can hot unplug the dimm in question.
I guess that's a bit of a high end though though... so maybe you don't care about it.
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