>>>>> "David" == David Mosberger <[EMAIL PROTECTED]> writes:
David> At the risk of asking the obvious: what's preventing genalloc David> to be implemented in terms of mempool? David, Taking another look at mempool, there's several reasons why mempool isn't well suited for this job. Basically for the uncached page case we want to first pull out all the spill pages in the lower granules[1] and only after those have been used, do we want to start converting pages from cached to uncached. mempool on the other hand will first try and call the user provided allocation function and only if that fails try and take memory from the pool, this will force us to convert pages from cached to uncached if we don't have to. The other issue is that mempool isn't designed to handle the case where you do not want to hand the memory back to the system using the user provided free() function, somehing which we can't even do for the spill pages and converting the normal pages back is a nightmare since you have to wait for a full granule to reappear. Last, mempool interacts quite a lot with the vm, kicking bdflush if it is unable to allocate memory which will not have any effect for these kinds of pages anyway. One could probably do this via mempool, but it would basically require one to put another object allocator below mempool which really makes the whole exercise pointless as this could just as well be done standalone ... ie. genalloc. Cheers, Jes [1]: For those who are interested, on ia64 one has to convert a full granule, 16MB, at a time in order to avoid data corruption due to the CPU might be doing speculative loads within a full granule. - 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/
