Re: [PATCH v8 2/4] perf inject: add jitdump mmap injection support

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Fri, Feb 05, 2016 at 10:57:17AM -0300, Arnaldo Carvalho de Melo escreveu:
> Duh:
> 
> [acme@jouet java]$ java -agentpath:/home/acme/git/linux/tools/perf/jvmti/libjvmti.so hello
> java: jvmti: jitdump in /home/acme/.debug/jit/java-jit-20160205.XXFb472a/jit-28966.dump
> Hello, World
> [acme@jouet java]$ 

Ok, so mucho progress:

[acme@jouet java]$ perf record -k 1 java -agentpath:/home/acme/git/linux/tools/perf/jvmti/libjvmti.so hello
java: jvmti: jitdump in /home/acme/.debug/jit/java-jit-20160205.XXIiqiq7/jit-31400.dump
Hello, World
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.030 MB perf.data (268 samples) ]
[acme@jouet java]$ perf inject --jit -i perf.data -o perf.data.jitted
[acme@jouet java]$ perf report -D -i perf.data | grep PERF_RECORD_MMAP > mmaps.before
Failed to open /tmp/perf-31400.map, continuing without symbols
[acme@jouet java]$ perf report -D -i perf.data. | grep PERF_RECORD_MMAP > mmaps.before
perf.data.jitted      perf.data.jitted.old  perf.data.old         
[acme@jouet java]$ perf report -D -i perf.data.jitted | grep PERF_RECORD_MMAP > mmaps.jitted
[acme@jouet java]$ diff -u mmaps.before mmaps.jitted
--- mmaps.before	2016-02-05 11:01:16.019257683 -0300
+++ mmaps.jitted	2016-02-05 11:01:28.966232802 -0300
<SNIP>
+77539479986521 0xfc80 [0xa0]: PERF_RECORD_MMAP2 31400/31413: [0x7f3f7d102880(0xc0) @ 0x40 fd:02 1840179 1]: --xs /home/acme/.debug/jit/java-jit-20160205.XXIiqiq7/jitted-31400-281.so
+77539480189814 0xfd20 [0xa0]: PERF_RECORD_MMAP2 31400/31413: [0x7f3f7d0fef60(0x80) @ 0x40 fd:02 1840180 1]: --xs /home/acme/.debug/jit/java-jit-20160205.XXIiqiq7/jitted-31400-282.so
+77539480541065 0xfdc0 [0xa0]: PERF_RECORD_MMAP2 31400/31413: [0x7f3f7d102560(0x180) @ 0x40 fd:02 1840181 1]: --xs /home/acme/.debug/jit/java-jit-20160205.XXIiqiq7/jitted-31400-283.so
+77539480541871 0xfe60 [0xa0]: PERF_RECORD_MMAP2 31400/31413: [0x7f3f7d102360(0x180) @ 0x40 fd:02 1840182 1]: --xs /home/acme/.debug/jit/java-jit-20160205.XXIiqiq7/jitted-31400-284.so
+77539480848667 0xff00 [0xa0]: PERF_RECORD_MMAP2 31400/31413: [0x7f3f7d102160(0x180) @ 0x40 fd:02 1840183 1]: --xs /home/acme/.debug/jit/java-jit-20160205.XXIiqiq7/jitted-31400-285.so
+77539480910925 0xffa0 [0xa0]: PERF_RECORD_MMAP2 31400/31413: [0x7f3f7d101f60(0x180) @ 0x40 fd:02 1840184 1]: --xs /home/acme/.debug/jit/java-jit-20160205.XXIiqiq7/jitted-31400-286.so
<SNIP>

Quite a lot of those, but I noticed this, probably harmless, at the start:

 0 0x3fd8 [0x88]: PERF_RECORD_MMAP -1/0: [0xffffffffa0991000(0x5000) @ 0]: x /lib/modules/4.3.4-300.fc23.x86_64/kernel/net/dns_resolver/dns_resolver.ko.xz
 0 0x4060 [0x78]: PERF_RECORD_MMAP -1/0: [0xffffffffa0996000(0x7b000) @ 0]: x /lib/modules/4.3.4-300.fc23.x86_64/kernel/fs/nfs/nfsv4.ko.xz
 0 0x40d8 [0x88]: PERF_RECORD_MMAP -1/0: [0xffffffffa0a11000(0x5f5eefff) @ 0]: x /lib/modules/4.3.4-300.fc23.x86_64/kernel/drivers/usb/storage/usb-storage.ko.xz
-77539437123281 0x6b98 [0xa0]: PERF_RECORD_MMAP2 31400/31400: [0x557b73152000(0x202000) @ 0 fd:00 7858 3897326142]: r-xp /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.71-1.b15.fc23.x86_64/jre/bin/java
+77539437123281 0x42a0 [0xa0]: PERF_RECORD_MMAP2 31400/31400: [0x557b73152000(0x202000) @ 0 fd:00 7858 3897326142]: r-xp /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.71-1.b15.fc23.x86_64/jre/bin/java

I.e. the MMAP records for the kernel modules comes in ok, humm, because
probably you don't hook on PERF_RECORD_MMAP in perf-inject, just on MMAP2, and
in those the only difference is the second field, 0x6b98 -> 0x42a0, what is
that?

static void dump_event(struct perf_evlist *evlist, union perf_event *event,
                       u64 file_offset, struct perf_sample *sample)
{
        if (sample)
                perf_evlist__print_tstamp(evlist, event, sample);

        printf("%#" PRIx64 " [%#x]: PERF_RECORD_%s", file_offset,
               event->header.size, perf_event__name(event->header.type));

File offset, what changed?

-0x7c18 [0x8]: event: 68
-.
-. ... raw event: size 8 bytes
-.  0000:  44 00 00 00 00 00 08 00                          D.......
-.
-0x7c18 [0x8]: PERF_RECORD_FINISHED_ROUND
-
-0x6a80 [0x28]: event: 9

Humm, inject doesn't preserves PERF_RECORD_FINISHED_ROUND? Or user events in
general? On purpose?

- Arnaldo