The happy path is storage ===>> RAM ==>> NIC, without CPU access. So there is basically a single memory write and a single memory read per byte. That's the

The happy path is storage ===>> RAM ==>> NIC, without CPU access. So there is basically a single memory write and a single memory read per byte. That's the non-TLS (and NIC TLS offload) path. Since TLS is per-connection and the page-cache is per-file, any software crypto needs to encrypt from a common source in the page cache to a per-client buffer (eg, it cannot happen in-place). So this introduces an extra memory read from the page cache and write to the per-client socket buffer. We use the non-temporal version of ISA-L, so as to write full cache lines into the socket buffer, and not pay for an extra memory read as part of a read-modify-write update of a partial cacheline. So software crypto basically doubles the memory bandwidth requirements over no TLS (or NIC TLS offload).