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Antonio SJ Musumeci
2024-04-07 23:39:34 -05:00
parent c3b580b3ff
commit 0cff2d7983
1 changed files with 28 additions and 3 deletions
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README.md
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@@ -168,9 +168,8 @@ These options are the same regardless of whether you use them with the
**cache.files=partial|full|auto-full|per-process** to limit double
caching. (default: false)
* **passthrough=BOOL**: On Linux 6.9 and above passthrough allows for
near native IO performance. cache.files=off will disable passthrough
but if direct-io-allow-mmap=true then mmap will be
passthroughed. `moveonenospc` will no longer function.
near native IO performance. See below for more details. (default:
false)
* **direct-io-allow-mmap=BOOL**: On Linux 6.6 and above it is
possible to disable file page caching while still allowing for
shared mmap support. mergerfs will enable this feature if available
@@ -415,6 +414,32 @@ fact it will not be automatically included.
**fuse** package.
### passthrough
With Linux 6.9 and above there is a feature in FUSE called
"passthrough" which can improve performance by allowing a union or
overlay filesystem (like mergerfs) to pass the file descriptor of a
file opened on an underlying filesystem to the kernel to work on
directly rather than calls always having to go to the FUSE server
(mergerfs). As of Linux 6.9 the functions that can be passthroughed
are regular file read/write IO and mmap. Other functions may be added
in the future.
Passthrough requires `cache.files` to be enabled. `cache.files=off`
(which enables FUSE direct-io feature) will override `passthrough` and
read/write requests will still be sent to mergerfs.
If `cache.files=off` and `direct-io-allow-mmap=true` (the default)
then regular read/write IO will be handled by mergerfs but mmap will
be passthroughed.
NOTE: `moveonenospc` will not work when using `passthrough` as it
removes mergerfs entirely from the read/write process. If an ENOSPC
error occurs it will be returned to the caller app immediately. Since
mergerfs won't be handling the IO it therefore won't be able to handle
any error returned by said IO.
### inodecalc
Inodes (st_ino) are unique identifiers within a filesystem. Each