On Fri, 18 May 2018, Dan Williams wrote: > On Fri, May 18, 2018 at 8:44 AM, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > > On Thu, Mar 08 2018 at 12:08pm -0500, > > Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > > > >> Mikulas sent this useful enhancement to the memcpy_flushcache API: > >> > >> https://patchwork.kernel.org/patch/10217655/ > >> > >> ...it's in my queue to either push through -tip or add it to the next > >> libnvdimm pull request for 4.17-rc1. > > > > Hi Dan, > > > > Seems this never actually went upstream. I've staged it in > > linux-dm.git's "for-next" for the time being: > > https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-4.18&id=a7e96990b5ff6206fefdc5bfe74396bb880f7e48 > > > > But do you intend to pick it up for 4.18 inclusion? If so I'll drop > > it.. would just hate for it to get dropped on the floor by getting lost > > in the shuffle between trees. > > > > Please avise, thanks! > > Mike > > Thanks for picking it up! I was hoping to resend it to get acks from > x86 folks, and then yes it fell through the cracks in my patch > tracking. > > Now that I look at it again I don't think we need this hunk: > > void memcpy_page_flushcache(char *to, struct page *page, size_t offset, > size_t len) > { > char *from = kmap_atomic(page); > - memcpy_flushcache(to, from + offset, len); > + __memcpy_flushcache(to, from + offset, len); > kunmap_atomic(from); > } Yes - this is not needed. > ...and I wonder what the benefit is of the 16-byte case? I would > assume the bulk of the benefit is limited to the 4 and 8 byte copy > cases. dm-writecache uses 16-byte writes frequently, so it is needed for that. If we split 16-byte write to two 8-byte writes, it would degrade performance for architectures where memcpy_flushcache needs to flush the cache. > Mikulas please resend with those comments addressed and include Ingo and > Thomas. Mikulas -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
