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authorJoel Fernandes <joelagnelf@nvidia.com>2026-07-18 13:15:36 -0400
committerPaul E. McKenney <paulmck@kernel.org>2026-07-23 10:39:57 -0700
commit34ff636f322c6d5e4f0a52338fa63a7dff09a495 (patch)
tree7629759c1ec7148b95bc8ab3080df20a5ecd2273 /Documentation/ABI/testing/sysfs-class-bdi
downloadlinux-stable-34ff636f322c6d5e4f0a52338fa63a7dff09a495.tar.gz
linux-stable-34ff636f322c6d5e4f0a52338fa63a7dff09a495.zip
scftorture: Count single_rpc offline failures in statistics outputgrafted
scf_torture_stats_print() aggregates each invoker thread's counters into a local scf_statistics structure before printing, but the n_single_rpc_ofl field is missing from the aggregation loop. As a result, the "single_rpc_ofl" value printed in the statistics line is always zero, even when smp_call_function_single() invocations for the RPC test have failed due to offline CPUs and been counted by the invoker threads. Add the missing accumulation so that the printed value reflects the actual counts. Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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+What: /sys/class/bdi/<bdi>/
+Date: January 2008
+Contact: Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
+
+Provide a place in sysfs for the backing_dev_info object. This allows
+setting and retrieving various BDI specific variables.
+
+The <bdi> identifier can be either of the following:
+
+MAJOR:MINOR
+
+ Device number for block devices, or value of st_dev on
+ non-block filesystems which provide their own BDI, such as NFS
+ and FUSE.
+
+MAJOR:MINOR-fuseblk
+
+ Value of st_dev on fuseblk filesystems.
+
+default
+
+ The default backing dev, used for non-block device backed
+ filesystems which do not provide their own BDI.
+
+What: /sys/class/bdi/<bdi>/read_ahead_kb
+Date: January 2008
+Contact: Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
+ Size of the read-ahead window in kilobytes
+
+ (read-write)
+What: /sys/class/bdi/<bdi>/min_ratio
+Date: January 2008
+Contact: Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
+ Under normal circumstances each device is given a part of the
+ total write-back cache that relates to its current average
+ writeout speed in relation to the other devices.
+
+ The 'min_ratio' parameter allows assigning a minimum
+ percentage of the write-back cache to a particular device.
+ For example, this is useful for providing a minimum QoS.
+
+ (read-write)
+
+What: /sys/class/bdi/<bdi>/min_ratio_fine
+Date: November 2022
+Contact: Stefan Roesch <shr@devkernel.io>
+Description:
+ Under normal circumstances each device is given a part of the
+ total write-back cache that relates to its current average
+ writeout speed in relation to the other devices.
+
+ The 'min_ratio_fine' parameter allows assigning a minimum reserve
+ of the write-back cache to a particular device. The value is
+ expressed as part of 1 million. For example, this is useful for
+ providing a minimum QoS.
+
+ (read-write)
+
+What: /sys/class/bdi/<bdi>/max_ratio
+Date: January 2008
+Contact: Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
+ Allows limiting a particular device to use not more than the
+ given percentage of the write-back cache. This is useful in
+ situations where we want to avoid one device taking all or
+ most of the write-back cache. For example in case of an NFS
+ mount that is prone to get stuck, or a FUSE mount which cannot
+ be trusted to play fair.
+
+ (read-write)
+
+What: /sys/class/bdi/<bdi>/max_ratio_fine
+Date: November 2022
+Contact: Stefan Roesch <shr@devkernel.io>
+Description:
+ Allows limiting a particular device to use not more than the
+ given value of the write-back cache. The value is given as part
+ of 1 million. This is useful in situations where we want to avoid
+ one device taking all or most of the write-back cache. For example
+ in case of an NFS mount that is prone to get stuck, or a FUSE mount
+ which cannot be trusted to play fair.
+
+ (read-write)
+
+What: /sys/class/bdi/<bdi>/min_bytes
+Date: October 2022
+Contact: Stefan Roesch <shr@devkernel.io>
+Description:
+ Under normal circumstances each device is given a part of the
+ total write-back cache that relates to its current average
+ writeout speed in relation to the other devices.
+
+ The 'min_bytes' parameter allows assigning a minimum
+ percentage of the write-back cache to a particular device
+ expressed in bytes.
+ For example, this is useful for providing a minimum QoS.
+
+ (read-write)
+
+What: /sys/class/bdi/<bdi>/max_bytes
+Date: October 2022
+Contact: Stefan Roesch <shr@devkernel.io>
+Description:
+ Allows limiting a particular device to use not more than the
+ given 'max_bytes' of the write-back cache. This is useful in
+ situations where we want to avoid one device taking all or
+ most of the write-back cache. For example in case of an NFS
+ mount that is prone to get stuck, a FUSE mount which cannot be
+ trusted to play fair, or a nbd device.
+
+ (read-write)
+
+What: /sys/class/bdi/<bdi>/strict_limit
+Date: October 2022
+Contact: Stefan Roesch <shr@devkernel.io>
+Description:
+ Forces per-BDI checks for the share of given device in the write-back
+ cache even before the global background dirty limit is reached. This
+ is useful in situations where the global limit is much higher than
+ affordable for given relatively slow (or untrusted) device. Turning
+ strictlimit on has no visible effect if max_ratio is equal to 100%.
+
+ (read-write)
+What: /sys/class/bdi/<bdi>/stable_pages_required
+Date: January 2008
+Contact: Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
+ If set, the backing device requires that all pages comprising a write
+ request must not be changed until writeout is complete.
+
+ (read-only)