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Diffstat (limited to 'Documentation/admin-guide/xfs.rst')
| -rw-r--r-- | Documentation/admin-guide/xfs.rst | 58 |
1 files changed, 52 insertions, 6 deletions
diff --git a/Documentation/admin-guide/xfs.rst b/Documentation/admin-guide/xfs.rst index 86de8a1ad91c..5422407a96d7 100644 --- a/Documentation/admin-guide/xfs.rst +++ b/Documentation/admin-guide/xfs.rst @@ -284,6 +284,9 @@ The following sysctls are available for the XFS filesystem: removes unused preallocation from clean inodes and releases the unused space back to the free pool. + fs.xfs.speculative_cow_prealloc_lifetime + This is an alias for speculative_prealloc_lifetime. + fs.xfs.error_level (Min: 0 Default: 3 Max: 11) A volume knob for error reporting when internal errors occur. This will generate detailed messages & backtraces for filesystem @@ -356,12 +359,13 @@ The following sysctls are available for the XFS filesystem: Deprecated Sysctls ================== -=========================== ================ - Name Removal Schedule -=========================== ================ -fs.xfs.irix_sgid_inherit September 2025 -fs.xfs.irix_symlink_mode September 2025 -=========================== ================ +=========================================== ================ + Name Removal Schedule +=========================================== ================ +fs.xfs.irix_sgid_inherit September 2025 +fs.xfs.irix_symlink_mode September 2025 +fs.xfs.speculative_cow_prealloc_lifetime September 2025 +=========================================== ================ Removed Sysctls @@ -495,3 +499,45 @@ the class and error context. For example, the default values for "metadata/ENODEV" are "0" rather than "-1" so that this error handler defaults to "fail immediately" behaviour. This is done because ENODEV is a fatal, unrecoverable error no matter how many times the metadata IO is retried. + +Workqueue Concurrency +===================== + +XFS uses kernel workqueues to parallelize metadata update processes. This +enables it to take advantage of storage hardware that can service many IO +operations simultaneously. This interface exposes internal implementation +details of XFS, and as such is explicitly not part of any userspace API/ABI +guarantee the kernel may give userspace. These are undocumented features of +the generic workqueue implementation XFS uses for concurrency, and they are +provided here purely for diagnostic and tuning purposes and may change at any +time in the future. + +The control knobs for a filesystem's workqueues are organized by task at hand +and the short name of the data device. They all can be found in: + + /sys/bus/workqueue/devices/${task}!${device} + +================ =========== + Task Description +================ =========== + xfs_iwalk-$pid Inode scans of the entire filesystem. Currently limited to + mount time quotacheck. + xfs-blockgc Background garbage collection of disk space that have been + speculatively allocated beyond EOF or for staging copy on + write operations. +================ =========== + +For example, the knobs for the quotacheck workqueue for /dev/nvme0n1 would be +found in /sys/bus/workqueue/devices/xfs_iwalk-1111!nvme0n1/. + +The interesting knobs for XFS workqueues are as follows: + +============ =========== + Knob Description +============ =========== + max_active Maximum number of background threads that can be started to + run the work. + cpumask CPUs upon which the threads are allowed to run. + nice Relative priority of scheduling the threads. These are the + same nice levels that can be applied to userspace processes. +============ =========== |