On Mon, Oct 23, 2017 at 09:25:35AM -0700, Mark Salyzyn wrote: > __memcpy_fromio and __memcpy_toio functions do not deal well with > harmonically unaligned addresses unless they can ultimately be > copied as quads (u64) to and from the destination. Without a > harmonically aligned relationship, they perform byte operations > over the entire buffer. > > Dropped the fragment that tried to align on the normal memory, > placing a priority on using quad alignment on the io-side. > > Removed the volatile on the source for __memcpy_toio as it is > unnecessary. > > This change was motivated by performance issues in the pstore driver. > On a test platform, measuring probe time for pstore, console buffer > size of 1/4MB and pmsg of 1/2MB, was in the 90-107ms region. Change > managed to reduce it to 10-25ms, an improvement in boot time. > > Signed-off-by: Mark Salyzyn <saly...@android.com> > Cc: Kees Cook <keesc...@chromium.org> > Cc: Anton Vorontsov <an...@enomsg.org> > Cc: Tony Luck <tony.l...@intel.com> > Cc: Catalin Marinas <catalin.mari...@arm.com> > Cc: Will Deacon <will.dea...@arm.com> > Cc: Anton Vorontsov <an...@enomsg.org> > Cc: linux-arm-ker...@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > > v2: > - simplify, do not try so hard, or through steps, to align on the > normal memory side, as it was a diminishing return. Dealing with > any pathological short cases was unnecessary since there does not > appear to be any. > - drop similar __memset_io changes completely.
I'm fine with the idea here, but can you leave the '8's alone and not replace them with sizeof(u64) please? I don't think it helps anybody, and we still use ++/-- for the u8 case. Will
