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__print_symbolic() is designed for exporting the print formatting table to
userspace and allows parsing tool, such as trace-cmd and perf, to analyze
trace log according to this print formatting table, meanwhile, by using
__print_symbolic()s, save space in the trace ring buffer.
original print format:
print fmt: "%s: %s: HDR:%s, CDB:%s", __get_str(str), __get_str(dev_name),
__print_hex(REC->hdr, sizeof(REC->hdr)),
__print_hex(REC->tsf, sizeof(REC->tsf))
after this change:
print fmt: "%s: %s: HDR:%s, CDB:%s",
print_symbolic(REC->str_t, {0, "send"},
{1, "complete"},
{2, "dev_complete"},
{3, "query_send"},
{4, "query_complete"},
{5, "query_complete_err"},
{6, "tm_send"},
{7, "tm_complete"},
{8, "tm_complete_err"}),
__get_str(dev_name), __print_hex(REC->hdr, sizeof(REC->hdr)),
__print_hex(REC->tsf, sizeof(REC->tsf))
Note: This patch just converts current __get_str(str) to __print_symbolic(),
the original tracing log will not be affected by this change, so it
doesn't break what current parsers expect.
Link: https://lore.kernel.org/r/20210105113446.16027-3-huobean@gmail.com
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.