diff options
Diffstat (limited to 'Documentation/admin-guide')
| -rw-r--r-- | Documentation/admin-guide/cgroup-v2.rst | 6 | ||||
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 14 | ||||
| -rw-r--r-- | Documentation/admin-guide/thunderbolt.rst | 23 | ||||
| -rw-r--r-- | Documentation/admin-guide/xfs.rst | 42 |
4 files changed, 68 insertions, 17 deletions
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 63521cd36ce5..1de8695c264b 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -1029,7 +1029,7 @@ All time durations are in microseconds. one number is written, $MAX is updated. cpu.pressure - A read-only nested-key file which exists on non-root cgroups. + A read-write nested-keyed file. Shows pressure stall information for CPU. See :ref:`Documentation/accounting/psi.rst <psi>` for details. @@ -1475,7 +1475,7 @@ PAGE_SIZE multiple when read back. reduces the impact on the workload and memory management. memory.pressure - A read-only nested-key file which exists on non-root cgroups. + A read-only nested-keyed file. Shows pressure stall information for memory. See :ref:`Documentation/accounting/psi.rst <psi>` for details. @@ -1714,7 +1714,7 @@ IO Interface Files 8:16 rbps=2097152 wbps=max riops=max wiops=max io.pressure - A read-only nested-key file which exists on non-root cgroups. + A read-only nested-keyed file. Shows pressure stall information for IO. See :ref:`Documentation/accounting/psi.rst <psi>` for details. diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 0936f5e9288b..a6c806557e25 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3458,20 +3458,6 @@ For example, to override I2C bus2: omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100 - oprofile.timer= [HW] - Use timer interrupt instead of performance counters - - oprofile.cpu_type= Force an oprofile cpu type - This might be useful if you have an older oprofile - userland or if you want common events. - Format: { arch_perfmon } - arch_perfmon: [X86] Force use of architectural - perfmon on Intel CPUs instead of the - CPU specific event set. - timer: [X86] Force use of architectural NMI - timer mode (see also oprofile.timer - for generic hr timer mode) - oops=panic Always panic on oopses. Default is to just kill the process, but there is a small probability of deadlocking the machine. diff --git a/Documentation/admin-guide/thunderbolt.rst b/Documentation/admin-guide/thunderbolt.rst index 613cb24c76c7..f18e881373c4 100644 --- a/Documentation/admin-guide/thunderbolt.rst +++ b/Documentation/admin-guide/thunderbolt.rst @@ -47,6 +47,9 @@ be DMA masters and thus read contents of the host memory without CPU and OS knowing about it. There are ways to prevent this by setting up an IOMMU but it is not always available for various reasons. +Some USB4 systems have a BIOS setting to disable PCIe tunneling. This is +treated as another security level (nopcie). + The security levels are as follows: none @@ -77,6 +80,10 @@ The security levels are as follows: Display Port in a dock. All PCIe links downstream of the dock are removed. + nopcie + PCIe tunneling is disabled/forbidden from the BIOS. Available in some + USB4 systems. + The current security level can be read from ``/sys/bus/thunderbolt/devices/domainX/security`` where ``domainX`` is the Thunderbolt domain the host controller manages. There is typically @@ -153,6 +160,22 @@ If the user still wants to connect the device they can either approve the device without a key or write a new key and write 1 to the ``authorized`` file to get the new key stored on the device NVM. +De-authorizing devices +---------------------- +It is possible to de-authorize devices by writing ``0`` to their +``authorized`` attribute. This requires support from the connection +manager implementation and can be checked by reading domain +``deauthorization`` attribute. If it reads ``1`` then the feature is +supported. + +When a device is de-authorized the PCIe tunnel from the parent device +PCIe downstream (or root) port to the device PCIe upstream port is torn +down. This is essentially the same thing as PCIe hot-remove and the PCIe +toplogy in question will not be accessible anymore until the device is +authorized again. If there is storage such as NVMe or similar involved, +there is a risk for data loss if the filesystem on that storage is not +properly shut down. You have been warned! + DMA protection utilizing IOMMU ------------------------------ Recent systems from 2018 and forward with Thunderbolt ports may natively diff --git a/Documentation/admin-guide/xfs.rst b/Documentation/admin-guide/xfs.rst index 86de8a1ad91c..6178153d3320 100644 --- a/Documentation/admin-guide/xfs.rst +++ b/Documentation/admin-guide/xfs.rst @@ -495,3 +495,45 @@ 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. +============ =========== |