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| -rw-r--r-- | libnetdata/procfile/README.md | 49 |
1 files changed, 24 insertions, 25 deletions
diff --git a/libnetdata/procfile/README.md b/libnetdata/procfile/README.md index 7037dc4ee..7487e6c63 100644 --- a/libnetdata/procfile/README.md +++ b/libnetdata/procfile/README.md @@ -1,4 +1,3 @@ - # PROCFILE procfile is a library for reading text data files (i.e `/proc` files) in the fastest possible way. @@ -15,49 +14,49 @@ The library also supported quoted words (i.e. strings within of which the separa Initially the caller: -- calls `procfile_open()` to open the file and allocate the structures needed. +- calls `procfile_open()` to open the file and allocate the structures needed. ### Iterations For each iteration, the caller: -- calls `procfile_readall()` to read updated contents. - This call also rewinds (`lseek()` to 0) before reading it. +- calls `procfile_readall()` to read updated contents. + This call also rewinds (`lseek()` to 0) before reading it. + + For every file, a [BUFFER](../buffer/) is used that is automatically adjusted to fit + the entire file contents of the file. So the file is read with a single `read()` call + (providing atomicity / consistency when the data are read from the kernel). + + Once the data are read, 2 arrays of pointers are updated: - For every file, a [BUFFER](../buffer/) is used that is automatically adjusted to fit - the entire file contents of the file. So the file is read with a single `read()` call - (providing atomicity / consistency when the data are read from the kernel). + - a `words` array, pointing to each word in the data read + - a `lines` array, pointing to the first word for each line - Once the data are read, 2 arrays of pointers are updated: + This is highly optimized. Both arrays are automatically adjusted to + fit all contents and are updated in a single pass on the data. - - a `words` array, pointing to each word in the data read - - a `lines` array, pointing to the first word for each line + The library provides a number of macros: - This is highly optimized. Both arrays are automatically adjusted to - fit all contents and are updated in a single pass on the data. - - The library provides a number of macros: - - - `procfile_lines()` returns the # of lines read - - `procfile_linewords()` returns the # of words in the given line - - `procfile_word()` returns a pointer the given word # - - `procfile_line()` returns a pointer to the first word of the given line # - - `procfile_lineword()` returns a pointer to the given word # of the given line # + - `procfile_lines()` returns the # of lines read + - `procfile_linewords()` returns the # of words in the given line + - `procfile_word()` returns a pointer the given word # + - `procfile_line()` returns a pointer to the first word of the given line # + - `procfile_lineword()` returns a pointer to the given word # of the given line # ### Cleanup When the caller exits: -- calls `procfile_free()` to close the file and free all memory used. +- calls `procfile_free()` to close the file and free all memory used. ### Performance -- a **raspberry Pi 1** (the oldest single core one) can process 5.000+ `/proc` files per second. -- a **J1900 Celeron** processor can process 23.000+ `/proc` files per second per core. +- a **raspberry Pi 1** (the oldest single core one) can process 5.000+ `/proc` files per second. +- a **J1900 Celeron** processor can process 23.000+ `/proc` files per second per core. To achieve this kind of performance, the library tries to work in batches so that the code and the data are inside the processor's caches. -This library is extensively used in netdata and its plugins. +This library is extensively used in Netdata and its plugins. -[]() +[](<>) |