On Tuesday 10 July 2007, Mel Gorman wrote: > > Mel's page allocator work. Might merge this, but I'm still not hearing > > sufficiently convincing noises from a sufficient number of people over > > this. > > This is a long on-going story. It bounces between people who say it's not a > complete solution and everything should have the 100% ability to defragment > and the people on the other side that say it goes a long way to solving > their problem. I've cc'd some of the parties that have expressed any > interest in the last year.
I find myself wondering what "sufficiently convincing noises" are. I think we can all agree that in the current kernel order>0 allocations are a disaster. They simply aren't useable once the system fragments. I think we can also all agree that 100% defragmentation is impossible without rewriting the kernel to avoid the hard-coded virtual->physical relationship we have now. With that said, the only remaining question I see is whether we need order>0 allocations. If we do, then Mel's patches are clearly the right thing to do. They have received a lot of testing (if just by virtue of being in -mm for so long), and have shown to greatly increase the availability of order>0 pages. The sheer list of patches lined up behind this set is strong evidence that there are useful features which depend on a working order>0. When you add in the existing code that has to struggle with allocation failures or resort to special pools (ie hugetlbfs), I see a clear vote for the need for this patch. Some object because order>0 will still be able to fail. I point out that order==0 can also fail, though we go to great lengths to prevent it. Mel's patches raise the success rate of order>0 to within a few percent of order==0. All this means is callers will need to decide how to handle the infrequent failure. This should be true no matter what the order. I strongly vote for merging these patches. Let's get them in mainline where they can do some good. Dave McCracken - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
