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102 lines
2.7 KiB
102 lines
2.7 KiB
libtraceevent(3) |
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================ |
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NAME |
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---- |
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tep_get_header_page_size, tep_get_header_timestamp_size, tep_is_old_format - |
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Get the data stored in the header page, in kernel context. |
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SYNOPSIS |
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-------- |
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[verse] |
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-- |
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*#include <event-parse.h>* |
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int *tep_get_header_page_size*(struct tep_handle pass:[*]_tep_); |
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int *tep_get_header_timestamp_size*(struct tep_handle pass:[*]_tep_); |
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bool *tep_is_old_format*(struct tep_handle pass:[*]_tep_); |
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-- |
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DESCRIPTION |
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----------- |
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These functions retrieve information from kernel context, stored in tracefs |
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events/header_page. Old kernels do not have header page info, so default values |
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from user space context are used. |
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The _tep_get_header_page_size()_ function returns the size of a long integer, |
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in kernel context. The _tep_ argument is trace event parser context. |
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This information is retrieved from tracefs events/header_page, "commit" field. |
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The _tep_get_header_timestamp_size()_ function returns the size of timestamps, |
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in kernel context. The _tep_ argument is trace event parser context. This |
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information is retrieved from tracefs events/header_page, "timestamp" field. |
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The _tep_is_old_format()_ function returns true if the kernel predates |
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the addition of events/header_page, otherwise it returns false. |
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RETURN VALUE |
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------------ |
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The _tep_get_header_page_size()_ function returns the size of a long integer, |
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in bytes. |
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The _tep_get_header_timestamp_size()_ function returns the size of timestamps, |
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in bytes. |
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The _tep_is_old_format()_ function returns true, if an old kernel is used to |
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generate the tracing data, which has no event/header_page. If the kernel is new, |
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or _tep_ is NULL, false is returned. |
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EXAMPLE |
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------- |
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[source,c] |
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-- |
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#include <event-parse.h> |
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... |
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struct tep_handle *tep = tep_alloc(); |
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... |
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int longsize; |
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int timesize; |
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bool old; |
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longsize = tep_get_header_page_size(tep); |
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timesize = tep_get_header_timestamp_size(tep); |
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old = tep_is_old_format(tep); |
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printf ("%s kernel is used to generate the tracing data.\n", |
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old?"Old":"New"); |
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printf("The size of a long integer is %d bytes.\n", longsize); |
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printf("The timestamps size is %d bytes.\n", timesize); |
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... |
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-- |
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FILES |
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----- |
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[verse] |
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-- |
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*event-parse.h* |
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Header file to include in order to have access to the library APIs. |
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*-ltraceevent* |
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Linker switch to add when building a program that uses the library. |
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-- |
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SEE ALSO |
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-------- |
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_libtraceevent(3)_, _trace-cmd(1)_ |
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AUTHOR |
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------ |
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[verse] |
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-- |
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*Steven Rostedt* <[email protected]>, author of *libtraceevent*. |
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*Tzvetomir Stoyanov* <[email protected]>, author of this man page. |
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-- |
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REPORTING BUGS |
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-------------- |
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Report bugs to <[email protected]> |
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LICENSE |
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------- |
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libtraceevent is Free Software licensed under the GNU LGPL 2.1 |
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RESOURCES |
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--------- |
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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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