On Wed, 14 Feb 2024 18:54:07 -0500 Steven Rostedt <rost...@goodmis.org> wrote:
> On Thu, 15 Feb 2024 08:45:52 +0900 > Masami Hiramatsu (Google) <mhira...@kernel.org> wrote: > > > > Hmm, the above is a fast path. I wonder if we should add a patch to make > > > that into: > > > > > > if (unlikely(size_bytes & (sizeof(long) - 1))) > > > data_size = DIV_ROUND_UP(size_bytes, sizeof(long)); > > > else > > > data_size = size_bytes >> (sizeof(long) == 4 ? 2 : 3); > > > > > > to keep from doing the division. > > > > OK, I thought DIV_ROUND_UP was not much cost. Since sizeof(long) is > > fixed 4 or 8, so > > > > data_size = (size_bytes + sizeof(long) - 1) >> BITS_PER_LONG; > > > > will this work? > > No, because BITS_PER_LONG is 32 or 64 ;-) Oops indeed. > > But this should; > > data_size = (size_bytes + sizeof(long) - 1) >> (sizeof(long) == 4 ? 2 : > 3); > > As sizeof(long) is a constant, that conditional expression will be hard > coded into either 2 or 3 by the compiler. Yeah. OK, let me update it. Thank you, > > -- Steve -- Masami Hiramatsu (Google) <mhira...@kernel.org>
