Messages in this thread | | | Subject | Re: 2.5.68-mm4 | From | (Eric W. Biederman) | Date | 03 May 2003 08:12:11 -0600 |
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Anton Blanchard <anton@samba.org> writes:
> Hi, > > > . Included the `kexec' patch - load Linux from Linux. Various people want > > this for various reasons. I like the idea of going from a login prompt to > > "Calibrating delay loop" in 0.5 seconds. > > One thing that bothers me about kexec is how we grab low pages in > kimage_alloc_page(). On a partitioned ppc64 box I will need to grab > memory in the low 256MB and the machine might have 500GB of memory > free. Thats going to take some time :)
Could you explain to me the need to allocate memory in the low 256MB. Generally the design is that you can allocate the memory anywhere and then relocate_kernel.S will move where it needs to be kept.
I have had people wanting to use 300MB initial ramdisks and the like. If you have 500GB of memory what is the point of keeping anything on a disk?
When you have 4TB on a cluster or a NUMA machine I can understand wanting to keep things local to a node. But in those cases you want to have local node zones so the problem does not come up.
In general I hate restricting the memory you can use, because kexec is not just about booting linux. But it is about booting anything that we reasonably can. The only case I have seen so far that makes sense is when your physical memory is larger than your virtual memory.
> Id hate to introduce a separate zone just for this sort of stuff (we > currently throw all memory in the DMA zone). Could we add a hint to > the page allocator where it makes a best effort to grab memory below > a threshold?
I suspect so. And I can't imagine it would be that hard to implement.
But I think I would like to see why you need that.
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