PE-to-PE latency: drop h5 inter-SIP panel from overview

Remove h5_inter_sip from the hop list and switch the overview grid
from 2x3 to 2x2. RAW DMA was unavailable for the cross-SIP hop, so
the panel only carried IPCQ data and was redundant with h4_inter_cube
for the topology comparison.

Regenerate pe2pe_latency_plots/overview.png and summary.csv; delete
the obsolete h5_inter_sip.png.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_pe_to_pe_latency.py

@@ -1,15 +1,12 @@
 """PE-to-PE latency sweep across hop types and data sizes.
 
-Compares IPCQ send/recv vs raw-DMA (tl.load + tl.store) latency for five
+Compares IPCQ send/recv vs raw-DMA (tl.load + tl.store) latency for four
 hop types:
 
   H1 Intra-cube horizontal   pe0 → pe1
   H2 Intra-cube vertical     pe0 → pe4
   H3 Inter-cube horizontal   sip0.cube0.pe0 → sip0.cube1.pe0
   H4 Inter-cube vertical     sip0.cube0.pe0 → sip0.cube4.pe0
-  H5 Inter-SIP               sip0.cube0.pe0 → sip1.cube0.pe0   (IPCQ only —
-                                                                raw needs
-                                                                cross-SIP MMU)
 
 Sizes: 128..10240 bytes. Emits PNGs with both lines plus a CSV.
 """
@@ -48,7 +45,7 @@ class Hop:
     dst: tuple[int, int, int]
     send_dir: str
     recv_dir: str
-    supports_raw: bool   # False for cross-SIP (DPPolicy intra-device only)
+    supports_raw: bool
 
 
 HOPS = [
@@ -60,8 +57,6 @@ HOPS = [
         (0, 0, 0), (0, 1, 0), "E", "W", True),
     Hop("h4_inter_cube_vertical", "Inter-cube vertical (cube0 to cube4)",
         (0, 0, 0), (0, 4, 0), "S", "N", True),
-    Hop("h5_inter_sip", "Inter-SIP (sip0 to sip1, same cube/pe)",
-        (0, 0, 0), (1, 0, 0), "global_E", "global_W", False),
 ]
 
 
@@ -251,12 +246,6 @@ def _plot_per_hop(records, hop: Hop, path: Path) -> None:
             [r["total_ns"] for r in raw],
             marker="s", label="Raw DMA (load+store)", color="tab:orange",
         )
-    else:
-        ax.text(
-            0.98, 0.02, "(Raw DMA unavailable for cross-SIP)",
-            transform=ax.transAxes, ha="right", va="bottom",
-            fontsize=9, color="gray",
-        )
     ax.set_xlabel("Data size (bytes)")
     ax.set_ylabel("Latency (ns)")
     ax.set_title(hop.label)
@@ -270,7 +259,7 @@ def _plot_per_hop(records, hop: Hop, path: Path) -> None:
 def _plot_overview(records, path: Path) -> None:
     import matplotlib.pyplot as plt
 
-    fig, axes = plt.subplots(2, 3, figsize=(16, 9))
+    fig, axes = plt.subplots(2, 2, figsize=(13, 9))
     axes = axes.flatten()
     for i, hop in enumerate(HOPS):
         ax = axes[i]