On 03/23/2010 09:44 PM, Benjamin Herrenschmidt wrote: > >> I though one possibility would be to have LMB regions become more lists >> than arrays, so that the static storage only needs to cover as much as >> is needed during really early boot (and we could probably still move the >> BSS top point on some archs to dynamically make more ... actually we >> could be smart arses and use LMB to allocate more LMB list heads if we >> are reaching the table limit :-) > > Actually what about that: > > LMB entries are linked-listed. The array is just storage for those entry > "heads". > > The initial static array only needs to be big enough for very very early > platform specific kernel bits and pieces, so it could even be sized by a > Kconfig option. Or it could just use a klimit moving trick to pick up a > page right after the BSS but that may need to be arch specific. > > lmb_init() queues all the entries from the initial array in a freelist > > lmb_alloc() and lmb_reserve() just pop entries from that freelist to > populate the two main linked lists (memory and reserved). > > When something tries to dequeue up the last freelist entry, then under > the hood, LMB uses it instead to allocate a new block of LMB entries > that gets added to the freelist. > > We never free blocks of LMB entries. > > That way, we can fine tine the static array to be as small as we can > realistically make it be, and we have no boundary limitations on the > amount of entries in either the memory list or the reserved list. > > I'm a bit too flat out right now to write code, but if there's no > objection, I might give that a go either later this week or next week, > see if I can replace bootmem on powerpc. > if the array can be doubled and have old one copied to new one. then we don't change lmb.c too much. new early_res.c exend lmb. and another half already works with x86 to replace bootmem. will check if i can produce one patch to make powerpc to reuse early_res/nobootmem Thanks Yinghai -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
