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55 lines
2.3 KiB
Markdown
55 lines
2.3 KiB
Markdown
# Tweaking Performance
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`mergerfs` is effectively a filesystem proxy and therefore its
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theoretical max performance is that of the underlying devices
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(ignoring caching performed by the kernel.) However, given it is a
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FUSE based filesystem working from userspace there is an increase in
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overhead relative to kernel based solutions. That said the performance
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can match the theoretical max but it depends greatly on the system's
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configuration. There are many things which can impact
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performance. Device speeds and latency, network speeds and latency,
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concurrency and parallel limits of the hardware, read/write sizes,
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etc.
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While some settings can impact performance they are all **functional**
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in nature. Meaning they change mergerfs' behavior in some way. As a
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result there is really no such thing as a "performance mode".
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If you're having performance concerns please read over the
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[benchmarking section](benchmarking.md) of these docs and then the
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details below.
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NOTE: Be sure to [read about available features](config/options.md)
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before changing them to understand how functionality will change.
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* test theoretical performance using `nullrw` or using a ram disk as a
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branch
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* enable [passthrough](config/passthrough.md) (likely to have the
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biggest impact)
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* change read or process [thread pools](config/threads.md)
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* toggle [func.readdir](config/func_readdir.md)
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* increase [readahead](config/readahead.md): `readahead=1024`
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* disable `security_capability` and/or [xattr](config/xattr.md)
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* increase cache timeouts [cache.attr](config/cache.md#cacheattr),
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[cache.entry](config/cache.md#cacheentry),
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[cache.negative_entry](config/cache.md#cachenegative_entry)
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* toggle [page caching](config/cache.md#cachefiles)
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* enable `parallel-direct-writes`
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* enable [cache.writeback](config/cache.md#cachewriteback)
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* enable [cache.statfs](config/cache.md#cachestatfs)
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* enable [cache.symlinks](config/cache.md#cachesymlinks)
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* enable [cache.readdir](config/cache.md#cachereaddir)
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* disable `posix_acl`
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* disable `async_read`
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* use [symlinkify](config/symlinkify.md) if your data is largely
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static and read-only
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* use [tiered cache](extended_usage_patterns.md) devices
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* use LVM and LVM cache to place a SSD in front of your HDDs
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## Additional Reading
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* [Benchmarking](benchmarking.md)
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* [Options](config/options.md)
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* [Tips and Notes](tips_notes.md)
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