[RFC PATCH 0/5] Experimenting with tb-lookup tweaks

[Alex Bennée]

Hi Richard,

Well I spun up some of the ideas we talked about to see if there was
anything to be squeezed out of the function. In the end the results
seem to be a washout with my pigz benchmark:

 qemu-system-aarch64 -cpu cortex-a57 \
   -machine type=virt,virtualization=on,gic-version=3 \
   -serial mon:stdio \
   -netdev user,id=unet,hostfwd=tcp::2222-:22 \
   -device virtio-net-pci,netdev=unet,id=virt-net,disable-legacy=on \
   -device virtio-scsi-pci,id=virt-scsi,disable-legacy=on \
   -blockdev 
driver=raw,node-name=hd,discard=unmap,file.driver=host_device,file.filename=/dev/zen-disk/debian-buster-arm64
 \
   -device scsi-hd,drive=hd,id=virt-scsi-hd \
   -smp 4 -m 4096 \
   -kernel ~/lsrc/linux.git/builds/arm64/arch/arm64/boot/Image \
   -append "root=/dev/sda2 systemd.unit=benchmark-pigz.service" \
   -display none -snapshot

| Command | Mean [s]       | Min [s] | Max [s] | Relative |
|---------+----------------+---------+---------+----------|
| Before  | 46.597 ± 2.482 |  45.208 |  53.618 |     1.00 |
| After   | 46.867 ± 2.242 |  45.871 |  53.180 |     1.00 |

Maybe the code cleanup itself makes it worthwhile. WDYT?

Alex Bennée (5):
  accel/tcg: rename tb_lookup__cpu_state and hoist state extraction
  accel/tcg: move CF_CLUSTER calculation to curr_cflags
  accel/tcg: drop the use of CF_HASH_MASK and rename params
  include/exec: lightly re-arrange TranslationBlock
  include/exec/tb-lookup: try and reduce branch prediction issues

 include/exec/exec-all.h   | 20 +++++++++++---------
 include/exec/tb-lookup.h  | 34 +++++++++++++++++-----------------
 accel/tcg/cpu-exec.c      | 31 ++++++++++++++++++-------------
 accel/tcg/tcg-runtime.c   |  6 ++++--
 accel/tcg/translate-all.c | 14 ++++++++------
 softmmu/physmem.c         |  2 +-
 6 files changed, 59 insertions(+), 48 deletions(-)

-- 
2.20.1