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authorLinus Torvalds <torvalds@linux-foundation.org>2024-01-11 19:46:52 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2024-01-11 19:46:52 -0800
commit5b9b41617bf3e1282cc60f07d3d52e62399aa4ba (patch)
treecff3bb6bac83d19a7afd9e6d637ec4d6480e5d0f /Documentation/trace
parentMerge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi (diff)
parentMAINTAINERS: use tabs for indent of CONFIDENTIAL COMPUTING THREAT MODEL (diff)
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Merge tag 'docs-6.8' of git://git.lwn.net/linux
Pull documentation update from Jonathan Corbet: "Another moderately busy cycle for documentation, including: - The minimum Sphinx requirement has been raised to 2.4.4, following a warning that was added in 6.2 - Some reworking of the Documentation/process front page to, hopefully, make it more useful - Various kernel-doc tweaks to, for example, make it deal properly with __counted_by annotations - We have also restored a warning for documentation of nonexistent structure members that disappeared a while back. That had the delightful consequence of adding some 600 warnings to the docs build. A sustained effort by Randy, Vegard, and myself has addressed almost all of those, bringing the documentation back into sync with the code. The fixes are going through the appropriate maintainer trees - Various improvements to the HTML rendered docs, including automatic links to Git revisions and a nice new pulldown to make translations easy to access - Speaking of translations, more of those for Spanish and Chinese ... plus the usual stream of documentation updates and typo fixes" * tag 'docs-6.8' of git://git.lwn.net/linux: (57 commits) MAINTAINERS: use tabs for indent of CONFIDENTIAL COMPUTING THREAT MODEL A reworked process/index.rst ring-buffer/Documentation: Add documentation on buffer_percent file Translated the RISC-V architecture boot documentation. Docs: remove mentions of fdformat from util-linux Docs/zh_CN: Fix the meaning of DEBUG to pr_debug() Documentation: move driver-api/dcdbas to userspace-api/ Documentation: move driver-api/isapnp to userspace-api/ Documentation/core-api : fix typo in workqueue Documentation/trace: Fixed typos in the ftrace FLAGS section kernel-doc: handle a void function without producing a warning scripts/get_abi.pl: ignore some temp files docs: kernel_abi.py: fix command injection scripts/get_abi: fix source path leak CREDITS, MAINTAINERS, docs/process/howto: Update man-pages' maintainer docs: translations: add translations links when they exist kernel-doc: Align quick help and the code MAINTAINERS: add reviewer for Spanish translations docs: ignore __counted_by attribute in structure definitions scripts: kernel-doc: Clarify missing struct member description ..
Diffstat (limited to 'Documentation/trace')
-rw-r--r--Documentation/trace/ftrace-uses.rst4
-rw-r--r--Documentation/trace/ftrace.rst17
2 files changed, 18 insertions, 3 deletions
diff --git a/Documentation/trace/ftrace-uses.rst b/Documentation/trace/ftrace-uses.rst
index f7d98ae5b885..e198854ace79 100644
--- a/Documentation/trace/ftrace-uses.rst
+++ b/Documentation/trace/ftrace-uses.rst
@@ -182,7 +182,7 @@ FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED
FTRACE_OPS_FL_RECURSION
By default, it is expected that the callback can handle recursion.
- But if the callback is not that worried about overehead, then
+ But if the callback is not that worried about overhead, then
setting this bit will add the recursion protection around the
callback by calling a helper function that will do the recursion
protection and only call the callback if it did not recurse.
@@ -190,7 +190,7 @@ FTRACE_OPS_FL_RECURSION
Note, if this flag is not set, and recursion does occur, it could
cause the system to crash, and possibly reboot via a triple fault.
- Not, if this flag is set, then the callback will always be called
+ Note, if this flag is set, then the callback will always be called
with preemption disabled. If it is not set, then it is possible
(but not guaranteed) that the callback will be called in
preemptable context.
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst
index 23572f6697c0..16122a8895ba 100644
--- a/Documentation/trace/ftrace.rst
+++ b/Documentation/trace/ftrace.rst
@@ -180,6 +180,21 @@ of ftrace. Here is a list of some of the key files:
Only active when the file contains a number greater than 0.
(in microseconds)
+ buffer_percent:
+
+ This is the watermark for how much the ring buffer needs to be filled
+ before a waiter is woken up. That is, if an application calls a
+ blocking read syscall on one of the per_cpu trace_pipe_raw files, it
+ will block until the given amount of data specified by buffer_percent
+ is in the ring buffer before it wakes the reader up. This also
+ controls how the splice system calls are blocked on this file::
+
+ 0 - means to wake up as soon as there is any data in the ring buffer.
+ 50 - means to wake up when roughly half of the ring buffer sub-buffers
+ are full.
+ 100 - means to block until the ring buffer is totally full and is
+ about to start overwriting the older data.
+
buffer_size_kb:
This sets or displays the number of kilobytes each CPU
@@ -2574,7 +2589,7 @@ want, depending on your needs.
- The cpu number on which the function executed is default
enabled. It is sometimes better to only trace one cpu (see
- tracing_cpu_mask file) or you might sometimes see unordered
+ tracing_cpumask file) or you might sometimes see unordered
function calls while cpu tracing switch.
- hide: echo nofuncgraph-cpu > trace_options