FD2 underperforms w/ multiple kernel binaries

[pgkeller]

FD2 doesn't pack kernel binaries.

Plan is for FD2.2 to use a ring buffer, w/ a the ring buffer the binaries can be packed in DRAM and written w/ one linear write

However, w/ multiple kernel groups, we'd still pay the dram latency for each kernel group which will dominate for typical kernel sizes.

To address both now and post ring buffer, we could:

1. Create a packed read command which would read from multiple dram locations
2. Either modify the existing packed write command to handle larger amounts of data (currently limited to 1 page per write) or create a packed_write_large command for larger transfers
3. Today, do a packed read followed by a packed_write for all binaries. Post ring buffer, we could pack the binaries for a kernel group in dram and then for single kernel groups do a read and linear write while multiple kernel groups would do a packed read and packed write (w/ fewer total transfers)

[pgkeller]

note that adding "force_inline" to a few prefetcher routines nets ~5% w/ 5 binaries.

[pgkeller]

Done, perf gains of >5x