SlugLab · vickiegpt · Aug 22, 2026 · Aug 20, 2026 · Aug 20, 2026 · Aug 20, 2026
diff --git a/.gitignore b/.gitignore
@@ -4,6 +4,7 @@ xctrace
 build
 cmake-*
 .vscode
+.worktrees/
 release
 benchmarks*
 Makefile

diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -177,6 +177,14 @@ target_include_directories(test_pgas_controller_counters PRIVATE include src ${s
 target_link_libraries(test_pgas_controller_counters cxlmemsim spdlog::spdlog_header_only ${RT_LIB} ${ATOMIC_LIB})
 add_test(NAME test_pgas_controller_counters COMMAND test_pgas_controller_counters)
 
+add_executable(test_pgas_poll_policy tests/test_pgas_poll_policy.cpp)
+target_include_directories(test_pgas_poll_policy PRIVATE include)
+add_test(NAME test_pgas_poll_policy COMMAND test_pgas_poll_policy)
+
+add_executable(test_cxl_memsim_wait_policy tests/test_cxl_memsim_wait_policy.c)
+target_include_directories(test_cxl_memsim_wait_policy PRIVATE lib/qemu/include)
+add_test(NAME test_cxl_memsim_wait_policy COMMAND test_cxl_memsim_wait_policy)
+
 add_executable(test_coherence_protocol_v2 tests/test_coherence_protocol_v2.cpp)
 target_include_directories(test_coherence_protocol_v2 PRIVATE include)
 target_link_libraries(test_coherence_protocol_v2 cxlmemsim)

diff --git a/artifact/pgas_fast_poll/2026-08-20T2255Z/README.md b/artifact/pgas_fast_poll/2026-08-20T2255Z/README.md
@@ -0,0 +1,82 @@
+# PGAS fast-poll live evidence
+
+## Configuration
+
+The server ran the synchronous PGAS shared-memory protocol with one polling
+worker and transport-only accounting:
+
+```text
+./build/cxlmemsim_server --comm-mode=pgas-shm \
+  --pgas-shm-name=/cxlmemsim_pgas --capacity=256 \
+  --pgas-workers=1 --pgas-spin-us=1000 --pgas-yield-count=10 \
+  --pgas-idle-sleep-us=100 --pgas-record-accesses=false
+```
+
+`record-accesses=false` skips the controller's linear per-address occupation
+history. It does not skip address validation, data reads/writes, synchronous
+responses, or protocol counters.
+
+The guest allocator mapped the working buffer `rw-s` from `/dev/dax0.0`, and
+the device remained bound to `/sys/bus/dax/drivers/device_dax`.
+
+## Adaptive-client result
+
+The exact guest command was:
+
+```text
+LD_PRELOAD=target/debug/libcxlalloc_preload.so \
+  /root/lmbench/bin/x86_64-linux-gnu/lat_mem_rd -t -N 4 128 64
+```
+
+The adaptive QEMU client completed all 115 numeric rows with no zero values and
+exit status 0. Its final row was:
+
+```text
+128.00000 5009.636
+```
+
+QEMU reported a 497.7 ns average successful server-response wait after
+771,000,000 operations. It also reported one isolated 100 millisecond response
+timeout; this is retained as a limitation even though the benchmark completed.
+
+## Original-wait mediated control
+
+The same QEMU integration checkout was rebuilt with the adaptive wait reverted.
+To avoid repeating the full logarithmic sweep, only the 128 MiB endpoint was
+selected while retaining `-N 4`:
+
+```text
+LD_PRELOAD=target/debug/libcxlalloc_preload.so \
+  /root/lmbench/bin/x86_64-linux-gnu/lat_mem_rd -t -N 4 \
+  -s 134217728 -e 134217728 128 64
+```
+
+That control exited 0 at:
+
+```text
+128.00000 31963.106
+```
+
+Server reads advanced from 404,900,000 to 430,000,000 and writes from
+370,898,371 to 400,260,303 during this endpoint, proving mediation. Relative
+to this control, adaptive polling reduced endpoint latency by 84.3%.
+
+## Rejected direct control
+
+An installed-QEMU run completed at 4062.530 ns/load, but the server log and
+counters did not advance during that run. It is retained as a non-mediated
+devdax lower-bound reference and is not used as evidence of server-path
+performance.
+
+## Correctness boundary
+
+- Adaptive run: 115 numeric rows, zero zero-valued rows, exit status 0.
+- Original-wait endpoint: one numeric row, exit status 0.
+- `/dev/dax0.0` remained in `devdax` mode.
+- No invalid-opcode trap or `lat_mem_rd` segfault appeared in either accepted
+  mediated run.
+
+The remaining approximately 5 microseconds includes KVM MMIO exit, QEMU
+dispatch, and a synchronous memory-server round trip. The approximately 4
+microsecond non-mediated result is not an achievable server-path target without
+changing the per-load mediation requirement.
diff --git a/artifact/pgas_fast_poll/2026-08-20T2255Z/acceptance-oldclient.after b/artifact/pgas_fast_poll/2026-08-20T2255Z/acceptance-oldclient.after
@@ -0,0 +1,5 @@
+boot_id=e1794343-43fe-41f0-bc19-bc1c84486528
+dmesg_lines=675
+invalid_opcode=0
+segfaults=0
+driver=/sys/bus/dax/drivers/device_dax
diff --git a/artifact/pgas_fast_poll/2026-08-20T2255Z/acceptance-oldclient.before b/artifact/pgas_fast_poll/2026-08-20T2255Z/acceptance-oldclient.before
@@ -0,0 +1,5 @@
+boot_id=e1794343-43fe-41f0-bc19-bc1c84486528
+dmesg_lines=675
+invalid_opcode=0
+segfaults=0
+driver=/sys/bus/dax/drivers/device_dax
diff --git a/artifact/pgas_fast_poll/2026-08-20T2255Z/acceptance.after b/artifact/pgas_fast_poll/2026-08-20T2255Z/acceptance.after
@@ -0,0 +1,14 @@
+2026-08-21T00:39:00Z
+bc9911b6-4ca8-4da6-bd9f-97d1e35daeed
+675
+0
+0
+[
+  {
+    "chardev":"dax0.0",
+    "size":262144000,
+    "target_node":1,
+    "align":2097152,
+    "mode":"devdax"
+  }
+]
diff --git a/artifact/pgas_fast_poll/2026-08-20T2255Z/acceptance.before b/artifact/pgas_fast_poll/2026-08-20T2255Z/acceptance.before
@@ -0,0 +1,5 @@
+2026-08-20T23:38:14Z
+bc9911b6-4ca8-4da6-bd9f-97d1e35daeed
+675
+0
+0
diff --git a/artifact/pgas_fast_poll/2026-08-20T2255Z/acceptance.summary b/artifact/pgas_fast_poll/2026-08-20T2255Z/acceptance.summary
@@ -0,0 +1,6 @@
+numeric_rows=115
+zero_rows=0
+final=128.00000 5009.636
+exit_status=0
+qemu_timeout_lines=1
+qemu_last_wait=qemu-system-x86_64: info: CXL Type3: PGAS response waits @ 771000000 ops: avg=497.7 ns, max=36712215 ns
diff --git a/artifact/pgas_fast_poll/2026-08-20T2255Z/devdax-transport.txt b/artifact/pgas_fast_poll/2026-08-20T2255Z/devdax-transport.txt
@@ -0,0 +1,29 @@
+{
+  "region":"region0",
+  "resource":45365592064,
+  "size":268435456,
+  "type":"pmem",
+  "interleave_ways":1,
+  "interleave_granularity":256,
+  "decode_state":"commit",
+  "mappings":[
+    {
+      "position":0,
+      "memdev":"mem0",
+      "decoder":"decoder2.0"
+    }
+  ],
+  "qos_class_mismatch":true
+}
+crw------- 1 root root 250, 0 Aug 20 23:37 /dev/dax0.0
+[
+  {
+    "chardev":"dax0.0",
+    "size":262144000,
+    "target_node":1,
+    "align":2097152,
+    "mode":"devdax"
+  }
+]
+driver=device_dax
+trap_count=0
diff --git a/artifact/pgas_fast_poll/2026-08-20T2255Z/lat_mem_rd-128m-endpoint-reverted.status b/artifact/pgas_fast_poll/2026-08-20T2255Z/lat_mem_rd-128m-endpoint-reverted.status
@@ -0,0 +1 @@
+0
diff --git a/artifact/pgas_fast_poll/2026-08-20T2255Z/lat_mem_rd-128m-endpoint-reverted.txt b/artifact/pgas_fast_poll/2026-08-20T2255Z/lat_mem_rd-128m-endpoint-reverted.txt
@@ -0,0 +1,2 @@
+"stride=64
+128.00000 31963.106
diff --git a/artifact/pgas_fast_poll/2026-08-20T2255Z/lat_mem_rd-128m-oldclient.status b/artifact/pgas_fast_poll/2026-08-20T2255Z/lat_mem_rd-128m-oldclient.status
@@ -0,0 +1 @@
+0
diff --git a/artifact/pgas_fast_poll/2026-08-20T2255Z/lat_mem_rd-128m-oldclient.txt b/artifact/pgas_fast_poll/2026-08-20T2255Z/lat_mem_rd-128m-oldclient.txt
@@ -0,0 +1,116 @@
+"stride=64
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+120.00000 4090.074
+128.00000 4062.530
diff --git a/artifact/pgas_fast_poll/2026-08-20T2255Z/lat_mem_rd-128m-transport.status b/artifact/pgas_fast_poll/2026-08-20T2255Z/lat_mem_rd-128m-transport.status
@@ -0,0 +1 @@
+0
-Original file line number
+Diff line change
@@ Expand Up / @@ -4,6 +4,7 @@ xctrace @@
     build
     cmake-*
     .vscode
+    .worktrees/
     release
     benchmarks*
     Makefile
@@ Expand Down @@
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,5 @@
		2026-08-20T23:38:14Z
		bc9911b6-4ca8-4da6-bd9f-97d1e35daeed
		675
		0
		0