Messages in this thread |  | | Date | Mon, 25 Sep 2000 18:04:48 +0200 | From | "Andi Kleen" <> | Subject | Re: the new VMt |
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On Mon, Sep 25, 2000 at 06:02:18PM +0200, Ingo Molnar wrote: > Frankly, how often do we allocate multi-order pages? I've just made quick > statistics wrt. how allocation orders are distributed on a more or less > typical system: > > (ALLOC ORDER) > 0: 167081 > 1: 850 > 2: 16 > 3: 25 > 4: 0 > 5: 1 > 6: 0 > 7: 2 > 8: 13 > 9: 5 > > ie. 99.45% of all allocations are single-page! 0.50% is the 8kb > task-structure. The rest is 0.05%.
An important exception in 2.2/2.4 is NFS with bigger rsize (will be fixed in 2.5, but 2.4 does it this way). For an 8K r/wsize you need reliable (=GFP_ATOMIC) 16K allocations.
Another thing I would worry about are ports with multiple user page sizes in 2.5. Another ugly case is the x86-64 port which has 4K pages but may likely need a 16K kernel stack due to the 64bit stack bloat.
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