Linda Knippers <linda.knippers@xxxxxx> writes: >> I'd be fine with changing the persistent memory block device to only >> support 4k logical, 4k physical block size. That probably makes the >> most sense. > > If that's what we want, the current patch doesn't do that. > https://lists.01.org/pipermail/linux-nvdimm/2015-July/001555.html > > It causes the physical block size to be PAGE_SIZE but the > logical block size is still 512. However, the minimum_io_size > is now 4096 (same as physical block size, I assume). The > optimal_io_size is still 0. What does that mean? physical block size - device's internal block size logical block size - addressable unit optimal io size - device's preferred unit for streaming minimum io size - device’s preferred minimum unit for random I/O See Martin Petersen's "Linux & Advanced Storage Interfaces" document for more information. > Whatever we go with, we should do something because 4.2rc6 is still > broken, unable to create a xfs file system on a pmem device, ever > since the change to use DAX on block devices with O_DIRECT. We can change the block device to export logical/physical block sizes of PAGE_SIZE. However, when persistent memory support comes to platforms that support page sizes > 32k, xfs will again run into problems (Dave Chinner mentioned that xfs can't deal with logical block sizes >32k.) Arguably, you can use pmem and dax on such platforms using RAM today for testing. Do we care about breaking that? Cheers, Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
