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42 lines
1.3 KiB
Markdown
42 lines
1.3 KiB
Markdown
# Heap profiling
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Cloud Hypervisor supports generating a profile using
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[dhat](https://docs.rs/dhat/latest/dhat/) of the heap allocations made during
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the runtime of the process.
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## Building a suitable binary
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This adds the symbol information to the release binary but does not otherwise
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affect the performance.
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```
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$ cargo build --profile profiling --features "dhat-heap"
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```
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## Generating output
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Cloud Hypervisor can then be run as usual. However it is necessary to run with `--seccomp false` as the profiling requires extra syscalls.
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```
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$ target/profiling/cloud-hypervisor \
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--kernel ~/src/linux/vmlinux \
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--pmem file=~/workloads/focal.raw \
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--cpus boot=1 --memory size=1G \
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--cmdline "root=/dev/pmem0p1 console=ttyS0" \
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--serial tty --console off \
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--api-socket /tmp/api1 \
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--seccomp false
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```
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When the VMM exits a message like the following will be shown:
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```
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dhat: Total: 384,582 bytes in 3,512 blocks
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dhat: At t-gmax: 133,885 bytes in 379 blocks
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dhat: At t-end: 12,160 bytes in 20 blocks
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dhat: The data has been saved to dhat-heap.json, and is viewable with dhat/dh_view.html
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```
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The JSON output can then be uploaded to [the dh_view tool](https://nnethercote.github.io/dh_view/dh_view.html) for analysis.
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