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ce9f1c05d2
When MMAP2 has the PERF_RECORD_MISC_MMAP_BUILD_ID flag, it means the
record already has the build-id info. So it marks the DSO as hit, to
skip if the same DSO is not processed if it happens to miss the build-id
later.
But it missed to copy the MMAP2 record itself so it'd fail to symbolize
samples for those regions.
For example, the following generates 249 MMAP2 events.
$ perf record --buildid-mmap -o- true | perf report --stat -i- | grep MMAP2
MMAP2 events: 249 (86.8%)
Adding perf inject should not change the number of events like this
$ perf record --buildid-mmap -o- true | perf inject -b | \
> perf report --stat -i- | grep MMAP2
MMAP2 events: 249 (86.5%)
But when --buildid-all is used, it eats most of the MMAP2 events.
$ perf record --buildid-mmap -o- true | perf inject -b --buildid-all | \
> perf report --stat -i- | grep MMAP2
MMAP2 events: 1 ( 2.5%)
With this patch, it shows the original number now.
$ perf record --buildid-mmap -o- true | perf inject -b --buildid-all | \
> perf report --stat -i- | grep MMAP2
MMAP2 events: 249 (86.5%)
Committer testing:
Before:
$ perf record --buildid-mmap -o- perf stat --null sleep 1 2> /dev/null | perf inject -b | perf report --stat -i- | grep MMAP2
MMAP2 events: 58 (36.2%)
$ perf record --buildid-mmap -o- perf stat --null sleep 1 2> /dev/null | perf report --stat -i- | grep MMAP2
MMAP2 events: 58 (36.2%)
$ perf record --buildid-mmap -o- perf stat --null sleep 1 2> /dev/null | perf inject -b --buildid-all | perf report --stat -i- | grep MMAP2
MMAP2 events: 2 ( 1.9%)
$
After:
$ perf record --buildid-mmap -o- perf stat --null sleep 1 2> /dev/null | perf inject -b | perf report --stat -i- | grep MMAP2
MMAP2 events: 58 (29.3%)
$ perf record --buildid-mmap -o- perf stat --null sleep 1 2> /dev/null | perf report --stat -i- | grep MMAP2
MMAP2 events: 58 (34.3%)
$ perf record --buildid-mmap -o- perf stat --null sleep 1 2> /dev/null | perf inject -b --buildid-all | perf report --stat -i- | grep MMAP2
MMAP2 events: 58 (38.4%)
$
Fixes:
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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.