On Fri, 2015-08-07 at 09:47 -0700, Dan Williams wrote: > On Thu, Aug 6, 2015 at 10:43 AM, Ross Zwisler > <ross.zwisler@xxxxxxxxxxxxxxx> wrote: > > Patch 5 adds support for the "read flush" _DSM flag, allowing us to change the > > ND BLK aperture mapping from write-combining to write-back via memremap_pmem(). > > > > Patch 6 updates the DAX I/O path so that all operations that store data (I/O > > writes, zeroing blocks, punching holes, etc.) properly synchronize the stores > > to media using the PMEM API. This ensures that the data DAX is writing is > > durable on media before the operation completes. > > > > Patches 1-4 are cleanup patches and additions to the PMEM API that make > > patches 5 and 6 possible. > > > > Regarding the choice to add both flush_cache_pmem() and wb_cache_pmem() to the > > PMEM API, I had initially implemented flush_cache_pmem() as a generic function > > flush_io_cache_range() in the spirit of flush_cache_range(), etc., in > > cacheflush.h. I eventually moved it into the PMEM API because a) it has a > > common and consistent use of the __pmem annotation, b) it has a clear fallback > > method for architectures that don't support it, as opposed to APIs in > > cacheflush.h which would need to be added individually to all other > > architectures. It can be argued that the flush API could apply to other uses > > beyond PMEM such as flushing cache lines associated with other types of > > sliding MMIO windows. At this point I'm inclined to have it as part of the > > PMEM API, and then take on the effort of making it a general cache flusing API > > if other users come along. > > I'm not convinced. There are already existing users for invalidating > a cpu cache and they currently jump through hoops to have cross-arch > flushing, see drm_clflush_pages(). What the NFIT-BLK driver brings to > the table is just one more instance where the cpu cache needs to be > invalidated, and for something so fundamental it is time we had a > cross arch generic helper. Fair enough. I'll move back to the flush_io_cache_range() solution. -- 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
