You signed in with another tab or window. Reload to refresh your session.You signed out in another tab or window. Reload to refresh your session.You switched accounts on another tab or window. Reload to refresh your session.Dismiss alert
Copy file name to clipboardExpand all lines: content/learning-paths/servers-and-cloud-computing/memory-subsystem/comparative-analysis.md
+11-11Lines changed: 11 additions & 11 deletions
Display the source diff
Display the rich diff
Original file line number
Diff line number
Diff line change
@@ -167,11 +167,11 @@ Peak bandwidth from `peak-bandwidth` shows the system-level memory controller ca
167
167
168
168
The credibility of this type of analysis comes from cross-validation. Check that:
169
169
170
-
1. Latency steps match cache sizes: the `latency-sweep` boundaries should align with the cache sizes reported by `sysfs` and the TRM.
171
-
2. Bandwidth plateaus match cache sizes: the `bandwidth-sweep` should show transitions at the same data sizes that `latency-sweep` identified.
172
-
3. Peak bandwidth matches documented limits: compare the "All Reads" figure from `peak-bandwidth` against the theoretical peak from `asct system-info`. A well-configured system typically achieves 85-95% of theoretical peak.
173
-
4. Idle loaded latency matches unloaded latency: the lowest-load row from `loaded-latency` should be close to the DRAM latency from `latency-sweep`.
174
-
5. Results are repeatable: run each benchmark at least twice. If results vary by more than 5%, investigate sources of noise (CPU frequency scaling, background processes).
170
+
- Latency steps match cache sizes: the `latency-sweep` boundaries should align with the cache sizes reported by `sysfs` and the TRM.
171
+
- Bandwidth plateaus match cache sizes: the `bandwidth-sweep` should show transitions at the same data sizes that `latency-sweep` identified.
172
+
- Peak bandwidth matches documented limits: compare the "All Reads" figure from `peak-bandwidth` against the theoretical peak from `asct system-info`. A well-configured system typically achieves 85-95% of theoretical peak.
173
+
- Idle loaded latency matches unloaded latency: the lowest-load row from `loaded-latency` should be close to the DRAM latency from `latency-sweep`.
174
+
- Results are repeatable: run each benchmark at least twice. If results vary by more than 5%, investigate sources of noise (CPU frequency scaling, background processes).
175
175
176
176
{{% notice Tip %}}
177
177
Check if your system allows you to control CPU frequency scaling during benchmarks for more consistent results:
@@ -184,18 +184,18 @@ echo performance | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governo
184
184
185
185
The examples here used AWS Graviton instances, but the methodology works on any Arm Linux machine with a NUMA-enabled kernel. To adapt it:
186
186
187
-
1. Install ASCT on the target system following the [install guide](/install-guides/asct/).
188
-
2. Run all memory benchmarks: `sudo asct run memory loaded-latency --format=csv --output-dir results_$(hostname)`
189
-
3. Compare with previous systems: `asct diff results_new/ --baseline results_reference/`
190
-
4. Cross-validate: check that latency boundaries, bandwidth plateaus, and peak numbers are consistent with each other and with the hardware documentation.
187
+
- Install ASCT on the target system following the [install guide](/install-guides/asct/).
188
+
- Run all memory benchmarks: `sudo asct run memory loaded-latency --format=csv --output-dir results_$(hostname)`
189
+
- Compare with previous systems: `asct diff results_new/ --baseline results_reference/`
190
+
- Cross-validate: check that latency boundaries, bandwidth plateaus, and peak numbers are consistent with each other and with the hardware documentation.
191
191
192
192
193
-
## What you've accomplished
193
+
## What you've learned
194
194
195
195
In this section you:
196
196
- Identified the topology and cache hierarchy of Arm Linux systems using `sysfs` and `asct system-info`
197
197
- Measured cache and memory latency with the ASCT `latency-sweep` benchmark
198
198
- Measured single-core streaming bandwidth with `bandwidth-sweep`
199
199
- Measured peak system bandwidth with `peak-bandwidth` and the latency-bandwidth tradeoff with `loaded-latency`
200
200
- Compared Graviton2 and Graviton4 to understand how generational improvements in core microarchitecture and memory technology affect real-world performance
201
-
- Developed a portable methodology that works on any Arm Linux system with a single command
201
+
- Developed a portable methodology that works on any Arm Linux system with a single command
0 commit comments