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author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-09-17 16:22:26 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-09-17 16:22:26 -0700 |
commit | 7c672abc120a55f678e5571ae2ee93f06ca4d7f9 (patch) | |
tree | 7beebc09f9626ca8d5f7df4dded0a553de479323 /Documentation/trace/ftrace.rst | |
parent | 1902314157b19754e0ff25b44527654847cfd127 (diff) | |
parent | fe013f8bc160d79c6e33bb66d9bb0cd24949274c (diff) |
Merge tag 'docs-5.4' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet:
"It's a somewhat calmer cycle for docs this time, as the churn of the
mass RST conversion is happily mostly behind us.
- A new document on reproducible builds.
- We finally got around to zapping the documentation for hardware
support that was removed in 2004; one doesn't want to rush these
things.
- The usual assortment of fixes, typo corrections, etc"
* tag 'docs-5.4' of git://git.lwn.net/linux: (67 commits)
Documentation: kbuild: Add document about reproducible builds
docs: printk-formats: Stop encouraging use of unnecessary %h[xudi] and %hh[xudi]
Documentation: Add "earlycon=sbi" to the admin guide
doc:lock: remove reference to clever use of read-write lock
devices.txt: improve entry for comedi (char major 98)
docs: mtd: Update spi nor reference driver
doc: arm64: fix grammar dtb placed in no attributes region
Documentation: sysrq: don't recommend 'S' 'U' before 'B'
mailmap: Update email address for Quentin Perret
docs: ftrace: clarify when tracing is disabled by the trace file
docs: process: fix broken link
Documentation/arm/samsung-s3c24xx: Remove stray U+FEFF character to fix title
Documentation/arm/sa1100/assabet: Fix 'make assabet_defconfig' command
Documentation/arm/sa1100: Remove some obsolete documentation
docs/zh_CN: update Chinese howto.rst for latexdocs making
Documentation: virt: Fix broken reference to virt tree's index
docs: Fix typo on pull requests guide
kernel-doc: Allow anonymous enum
Documentation: sphinx: Don't parse socket() as identifier reference
Documentation: sphinx: Add missing comma to list of strings
...
Diffstat (limited to 'Documentation/trace/ftrace.rst')
-rw-r--r-- | Documentation/trace/ftrace.rst | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index f60079259669..e3060eedb22d 100644 --- a/Documentation/trace/ftrace.rst +++ b/Documentation/trace/ftrace.rst @@ -125,7 +125,8 @@ of ftrace. Here is a list of some of the key files: This file holds the output of the trace in a human readable format (described below). Note, tracing is temporarily - disabled while this file is being read (opened). + disabled when the file is open for reading. Once all readers + are closed, tracing is re-enabled. trace_pipe: @@ -139,8 +140,9 @@ of ftrace. Here is a list of some of the key files: will not be read again with a sequential read. The "trace" file is static, and if the tracer is not adding more data, it will display the same - information every time it is read. This file will not - disable tracing while being read. + information every time it is read. Unlike the + "trace" file, opening this file for reading will not + temporarily disable tracing. trace_options: @@ -3153,7 +3155,10 @@ different. The trace is live. Note, reading the trace_pipe file will block until more input is -added. +added. This is contrary to the trace file. If any process opened +the trace file for reading, it will actually disable tracing and +prevent new entries from being added. The trace_pipe file does +not have this limitation. trace entries ------------- |