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Date: Fri, 27 Apr 2007 20:08:38 +1000 From: Nick Piggin <nickpiggin@...oo.com.au> To: Christoph Lameter <clameter@....com> CC: David Chinner <dgc@....com>, "Eric W. Biederman" <ebiederm@...ssion.com>, linux-kernel@...r.kernel.org, Mel Gorman <mel@...net.ie>, William Lee Irwin III <wli@...omorphy.com>, Jens Axboe <jens.axboe@...cle.com>, Badari Pulavarty <pbadari@...il.com>, Maxim Levitsky <maximlevitsky@...il.com> Subject: Re: [00/17] Large Blocksize Support V3 Christoph Lameter wrote: > On Thu, 26 Apr 2007, Nick Piggin wrote: > > >>Christoph Lameter wrote: >> >>>On Thu, 26 Apr 2007, Nick Piggin wrote: >>> >>> >>> >>>>But I maintain that the end result is better than the fragmentation >>>>based approach. A lot of people don't actually want a bigger page >>>>cache size, because they want efficient internal fragmentation as >>>>well, so your radix-tree based approach isn't really comparable. >>> >>> >>>Me? Radix tree based approach? That approach is in the kernel. Do not create >>>a solution where there is no problem. If we do not want to support large >>>blocksizes then lets be honest and say so instead of redefining what a block >>>is. The current approach is fine if one is satisfied with scatter gather and >>>the VM overhead coming with handling these pages. I fail to see what any of >>>what you are proposing would add to that. >> >>I'm not just making this up. Fragmentation. OK? > > > Yes you are. If you want to avoid fragmentation by restricting the OS to > 4k alone then the radix tree is sufficient to establish the order of pages > in a mapping. The only problem is to get an array of pointers to a > sequence of pages together by reading through the radix tree. I do not > know what else would be needed. No. We have avoided fragmentation up until now. We avoid fragmentation like the plague because it is crap. What _I_ do not want to do is add some patches that make it work a bit better and everyone think's that's a signal that it is a good idea to start using higher order allocations wherever possible. -- SUSE Labs, Novell Inc. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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