tmpfs for Super Fast Writes

Disk performance can be an important factor in CI/CD pipeline performance. It's affected by:

• Throughput: how much data you're writing or reading, especially sequentially
• IOPS: how many individual I/O operations are being performed, especially on small files
• Latency: how quickly each operation completes

The performance is mostly relevant in write-heavy tasks. And no task is heavier on the writes than an npm install, as hundreds of thousands of tiny files are written to disk.

#tmpfs

To accelerate performance in high iops scenarios like an npm install, we built support for running a task using tmpfs.

To use tmpfs, just add tmpfs: true to the agent configuration on your task.

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tasks:
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  - key: tmpfs-demo
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    agent:
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      tmpfs: true
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    run: ...

Here's a longer example of writing a gigabyte of 0's.

Without tmpfs, it takes 3.376s to write this file.

With tmpfs, it takes 0.383s (8.8x faster).

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tasks:
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  - key: tmpfs-demo
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    agent:
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      tmpfs: true
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    run: |
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      time dd \
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        if=/dev/zero \
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        of=testfile \
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        bs=1M \
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        count=1024 \
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        oflag=direct \
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        status=progress

#Demo