On 05/17/2012 05:32 PM, Paul Mundt wrote: > On Wed, May 16, 2012 at 11:05:17AM +0900, Minchan Kim wrote: >> About local_flush_tlb_kernel_range, >> If architecture is very smart, it could flush only tlb entries related to vaddr. >> If architecture is smart, it could flush only tlb entries related to a CPU. >> If architecture is _NOT_ smart, it could flush all entries of all CPUs. >> So, it would be best to support both portability and performance. >> > .. > >> Need double check about supporting local_flush_tlb_kernel_range >> in ARM, MIPS, SUPERH maintainers. And I will Ccing unicore32 and >> score maintainers because arch directory in those arch have >> local_flush_tlb_kernel_range, too but I'm very unfamiliar with those >> architecture so pass it to maintainers. >> I didn't coded up dumb local_flush_tlb_kernel_range which flush >> all cpus. I expect someone need ZSMALLOC will implement it easily in future. >> > > One thing you might consider is providing a stubbed definition that wraps > to flush_tlb_kernel_range() in the !SMP case, as this will extend your > testing coverage for staging considerably. > > Once you exclude all of the non-SMP platforms, you're left with the > following: > > - blackfin: doesn't count, no TLB to worry about. > - hexagon: seems to imply that the SMP case uses thread-based > CPUs that share an MMU, so no additional cost. > - ia64: Does a global flush, which already has a FIXME comment. > - m32r, mn10300: local_flush_tlb_all() could be wrapped. > - parisc: global flush? > - s390: Tests the cpumask to do a local flush, otherwise has a > __tlb_flush_local() that can be wrapped. > - sparc32: global flush > - sparc64: __flush_tlb_kernel_range() looks like a local flush. > - tile: does strange hypervisory things, presumably global. > - x86: has a local_flush_tlb() that could be wrapped. > > Which doesn't look quite that bad. You could probably get away with a > Kconfig option for optimized local TLB flushing or something, since > single function Kconfig options seem to be all the rage these days. I missed this sentence. Thanks for very helpful comment, Paul! -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>