> On Feb 2, 2019, at 12:02 PM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > > On Fri, Feb 01, 2019 at 02:57:47PM -0500, Chuck Lever wrote: >> Byte-swapping causes a CPU pipeline bubble on some processors. When >> a decoder is comparing an on-the-wire value for equality, byte- >> swapping can be avoided by comparing it directly to a pre-byte- >> swapped constant value. > > Which ones? I assume you mean on which processors have I observed CPU cycle spikes around bswap instructions. I've seen this behavior only on Intel processors of various families. Would you prefer a different justification for this clean-up? -- Chuck Lever
