Direct IPC Timing Evidence — 2026-07-27
This bundle supports the
Direct IPC Handoff Timing record.
The source state is the commit that adds this page; its commit message names
the retained run directory target/ipc-direct-switch/20260727T022642Z/.
Invocation and host envelope
All five samples ran in the foreground with:
CAPOS_MEASURE_QEMU_TASKSET_CPUS=0 \
CAPOS_MEASURE_ARTIFACT_DIR=target/ipc-direct-switch/20260727T022642Z/run-N \
make run-measure
The run interval was 2026-07-27 02:27:31–02:29:07 UTC. QEMU 8.2.2 used
-enable-kvm, one default qemu64 vCPU, 256 MiB guest RAM, and host logical
CPU 0 through taskset. The host exposed eight logical CPUs, four cores, two
threads per core, and an Intel Xeon 2.80 GHz CPU under KVM. Pinning constrained
QEMU’s process affinity; it did not isolate the host CPU from other work.
The selected host metadata is in
host.txt, and the shared command template is in
invocation.txt. These historical
invocation files retained a placeholder for the manifest-derived serial
arguments and did not bind the ISO or source commit, so they are not exact
build-provenance records. Current make run-measure artifact capture records
the resolved serial arguments, source commit and cleanliness, and ISO SHA-256.
Each sample also retains its own command template and terminal output:
| Run | Invocation | Kernel serial | Terminal |
|---|---|---|---|
| 1 | run-1 | run-1 | run-1 |
| 2 | run-2 | run-2 | run-2 |
| 3 | run-3 | run-3 | run-3 |
| 4 | run-4 | run-4 | run-4 |
| 5 | run-5 | run-5 | run-5 |
Extracted observations
| Run | CALL-to-receiver mean cycles | Direct selections | Ready-to-selection mean cycles | Minimum | Maximum |
|---|---|---|---|---|---|
| 1 | 8,331,819 | 71 | 414,989 | 384,829 | 494,458 |
| 2 | 8,046,901 | 71 | 407,062 | 381,529 | 534,133 |
| 3 | 7,924,721 | 71 | 396,515 | 378,951 | 499,971 |
| 4 | 7,757,445 | 72 | 387,503 | 378,337 | 523,416 |
| 5 | 7,845,114 | 72 | 394,393 | 378,660 | 476,480 |
The CALL-to-receiver column contains all 64 measured workload rounds. The boot-global direct-selection counter is not correlated with individual rounds, so the table does not claim that every CALL-to-receiver sample used the direct target. The ready-to-selection columns summarize only selections observed by the direct-target scheduler instrumentation. The five-run ranges characterize this 96-second collection window only; they are not reproducibility bounds.
The serial logs retain QEMU’s CRLF output. The SHA-256 digests below are for
their LF-normalized contents (tr -d '\r' < run-N-kernel.txt | sha256sum):
258b24e237abf185c271bac1b1308b6282e7cf7149b60beb5978ac363af07f92 run-1-kernel.txt
6bb099ec512faa75111651ad5c846a4dd667cbd746a2e51896bc5f3b852ee034 run-2-kernel.txt
a7876389a080c630cee177e11fa9686dcbf3872f382bdb08d318f2b65e5ac1d2 run-3-kernel.txt
098984217fdaccca8fb131a5d1bedcc790174aa18563f5c962ff9c13c204a509 run-4-kernel.txt
5add0328109003542897ec49809ff007b53546be84ef737d801eef88dc73b5d5 run-5-kernel.txt
The QEMU terminal files contain only the host’s unsupported-SVM-feature
warning. tools/qemu-measure-smoke.sh verified that no process output leaked
onto that UART and that every run completed the direct-IPC assertions.