On (11/03/07 09:44), Christoph Lameter didst pronounce: > On Sun, 11 Mar 2007, Andi Kleen wrote: > > > This and i386 version are ok to me, although it might be better to just > > finish __GFP_ZERO support to do this. > > This would not work for pgds on i386 and x86_64 > > GFP_ZERO support the way I have done it in the past would mean another set > of buddy lists in the page allocator and another issue with fragmentation. > So I have stayed away from it although patches exist in my archives (See > my ftp.kernel.org archive).
I haven't checked this in a while but when we experimented with keeping zero'd pages on separate lists before, the performance sucked. I haven't looked at it in a *long* time though. > > Maybe we could implemento limited GFP_ZERO support by just keeping an > additional per cpu list of pages? I imagine that adding an additional per-cpu list will not be welcome. > The issue with that one is that a page > may grow cold on that list. And that growing cold appeared to hurt before. It could be checked out again though. The anti-fragmentation breaks out the buddy lists already and has the ability to search the per-cpu lists for pages of an appropriate type. I'll try and find an hour or two to hack something together to see what it looks like but I suspect it'll still be a performance loss. At least then though, we can see if quicklists are a better plan or not. > One usually want the page to be hot in the > cache when it is allocated. This is different for page table pages. Page > table pages are typically sparsely accessed. > - > 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/ -- -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab - 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/
