perf(nsys): reduce CPU-side overhead in profiling defaults#3311
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dingqingy-nv wants to merge 3 commits intoNVIDIA-NeMo:mainfrom
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perf(nsys): reduce CPU-side overhead in profiling defaults#3311dingqingy-nv wants to merge 3 commits intoNVIDIA-NeMo:mainfrom
dingqingy-nv wants to merge 3 commits intoNVIDIA-NeMo:mainfrom
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Override nemo_run's default nsys_extra_args to disable CPU context-switch tracing (--cpuctxsw=none), backtrace collection (--backtrace=none), and CUDA graph node tracing (remove --cuda-graph-trace=node). These flags eliminate unnecessary CPU-side activity during GPU profiling. Signed-off-by: Dingqing Yang <dingqingy@nvidia.com> Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Dingqing Yang <dingqingy@nvidia.com>
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Signed-off-by: Dingqing Yang <dingqingy@nvidia.com> Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Dingqing Yang <dingqingy@nvidia.com>
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Let's treat this as an test PR. If getting less profiling overhead, we can raise a PR directly to nemo run and close this |
Instead of hardcoding the full nsys_extra_args list, filter out --cuda-graph-trace and append --cpuctxsw=none and --backtrace=none to the existing nemo_run defaults. This preserves forward compatibility with future nemo_run default changes. Signed-off-by: Dingqing Yang <dingqingy@nvidia.com> Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Dingqing Yang <dingqingy@nvidia.com>
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Summary
nsys_extra_argsto disable CPU context-switch tracing (--cpuctxsw=none), backtrace collection (--backtrace=none), and remove CUDA graph node tracing (--cuda-graph-trace=node)NsysPluginimplementations (recipes + perf scripts) and the interactive launch scriptChanges vs nemo_run defaults
--cpuctxswprocess-tree(nsys default)none--backtraceauto(nsys default)none--cuda-graph-tracenodeSince
-s none(disable CPU sampling) is already set by nemo_run,--backtrace=noneis defensive — there are no CPU samples to attach backtraces to.--cpuctxsw=noneis the main win, stopping OS thread scheduling trace collection that was active by default.Test plan
.nsys-repfilesnsys_extra_argsuser override still works (user args take precedence)🤖 Generated with Claude Code