55 lines
2.0 KiB
Markdown
55 lines
2.0 KiB
Markdown
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# Slab Input Plugin
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This plugin collects details on how much memory each entry in Slab cache is
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consuming. For example, it collects the consumption of `kmalloc-1024` and
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`xfs_inode`. Since this information is obtained by parsing `/proc/slabinfo`
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file, only Linux is supported. The specification of `/proc/slabinfo` has
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not changed since [Linux v2.6.12 (April 2005)](https://github.com/torvalds/linux/blob/1da177e4/mm/slab.c#L2848-L2861),
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so it can be regarded as sufficiently stable. The memory usage is
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equivalent to the `CACHE_SIZE` column of `slabtop` command.
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If the HOST_PROC environment variable is set, Telegraf will use its value instead of `/proc`
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**Note: `/proc/slabinfo` is usually restricted to read as root user. Make sure telegraf can execute `sudo` without password.**
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## Configuration
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```toml
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# Get slab statistics from procfs
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[[inputs.slab]]
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# no configuration - please see the plugin's README for steps to configure
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# sudo properly
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```
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## Sudo configuration
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Since the slabinfo file is only readable by root, the plugin runs `sudo /bin/cat` to read the file.
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Sudo can be configured to allow telegraf to run just the command needed to read the slabinfo file. For example, if telegraf is running as the user 'telegraf' and HOST_PROC is not used, add this to the sudoers file:
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`telegraf ALL = (root) NOPASSWD: /bin/cat /proc/slabinfo`
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## Metrics
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Metrics include generic ones such as `kmalloc_*` as well as those of kernel
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subsystems and drivers used by the system such as `xfs_inode`.
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Each field with `_size` suffix indicates memory consumption in bytes.
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- mem
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- fields:
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- kmalloc_8_size (integer)
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- kmalloc_16_size (integer)
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- kmalloc_32_size (integer)
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- kmalloc_64_size (integer)
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- kmalloc_96_size (integer)
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- kmalloc_128_size (integer)
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- kmalloc_256_size (integer)
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- kmalloc_512_size (integer)
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- xfs_ili_size (integer)
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- xfs_inode_size (integer)
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## Example Output
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```shel
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slab
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kmalloc_1024_size=239927296i,kmalloc_512_size=5582848i 1651049129000000000
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```
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