[PATCH 18/18] perf script: Allow specifying the files to process guest samples

Arnaldo Carvalho de Melo
2019-07-03T03:29:13Z

From: Arnaldo Carvalho de Melo <acme@redhat.com>

The 'perf kvm' command set up things so that we can record, report, top,
etc, but not 'script', so make 'perf script' be able to process samples
by allowing to pass guest kallsyms, vmlinux, modules, etc, and if at
least one of those is provided, set perf_guest to true so that guest
samples get properly resolved.

Testing it:

# perf kvm --guest --guestkallsyms /wb/rhel6.kallsyms --guestmodules /wb/rhel6.modules record -e cycles:Gk
^C[ perf record: Woken up 7 times to write data ]
[ perf record: Captured and wrote 3.602 MB perf.data.guest (10492 samples) ]

#
# perf evlist -i perf.data.guest
cycles:Gk
# perf evlist -v -i perf.data.guest
cycles:Gk: size: 112, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD, read_format: ID, disabled: 1, inherit: 1, exclude_user: 1, exclude_hv: 1, mmap: 1, comm: 1, freq: 1, task: 1, sample_id_all: 1, exclude_host: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1
#
# perf kvm --guestkallsyms /wb/rhel6.kallsyms --guestmodules /wb/rhel6.modules report --stdio -s sym | head -30
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 10K of event 'cycles:Gk'
# Event count (approx.): 2434201408
#
# Overhead Symbol
# ........ ..............................................
#
11.93% [g] avtab_search_node
3.95% [g] sidtab_context_to_sid
2.41% [g] n_tty_write
2.20% [g] _spin_unlock_irqrestore
1.37% [g] _aesni_dec4
1.33% [g] kmem_cache_alloc
1.07% [g] native_write_cr0
0.99% [g] kfree
0.95% [g] _spin_lock
0.91% [g] __memset
0.87% [g] schedule
0.83% [g] _spin_lock_irqsave
0.76% [g] __kmalloc
0.67% [g] avc_has_perm_noaudit
0.66% [g] kmem_cache_free
0.65% [g] glue_xts_crypt_128bit
0.59% [g] __d_lookup
0.59% [g] __audit_syscall_exit
0.56% [g] __memcpy
#

Then, when trying to use perf script to generate a python script and
then process the events after adding a python hook for non-tracepoint
events:

# perf script -i perf.data.guest -g python
generated Python script: perf-script.py
# vim perf-script.py
# tail -2 perf-script.py
def process_event(param_dict):
print(param_dict["symbol"])
#
# perf script -i perf.data.guest -s perf-script.py | head
in trace_begin
vmx_vmexit
vmx_vmexit
vmx_vmexit
vmx_vmexit
vmx_vmexit
vmx_vmexit
vmx_vmexit
vmx_vmexit
vmx_vmexit
231
#

We'd see just the vmx_vmexit, i.e. the samples from the guest don't show
up.

After this patch:

# perf script --guestkallsyms /wb/rhel6.kallsyms --guestmodules /wb/rhel6.modules -i perf.data.guest -s perf-script.py 2> /dev/null | head -30
in trace_begin
apic_timer_interrupt
apic_timer_interrupt
apic_timer_interrupt
apic_timer_interrupt
apic_timer_interrupt
save_args
do_timer
drain_array
inode_permission
avc_has_perm_noaudit
run_timer_softirq
apic_timer_interrupt
apic_timer_interrupt
apic_timer_interrupt
apic_timer_interrupt
apic_timer_interrupt
kvm_guest_apic_eoi_write
run_posix_cpu_timers
_spin_lock
handle_pte_fault
rcu_irq_enter
delay_tsc
delay_tsc
native_read_tsc
apic_timer_interrupt
sys_open
internal_add_timer
list_del
rcu_exit_nohz
#

Jiri Olsa noticed we need to set 'perf_guest' to true if we want to
process guest samples and I made it be set if one of the guest files
settings get set via the command line options added in this patch, that
match those present in the 'perf kvm' command.

We probably want to have 'perf record', 'perf report' etc to notice that
there are guest samples and do the right thing, which is to look for
files with some suffix that make it be associated with the guest used to
collect the samples, i.e. if a vmlinux file is passed, we can get the
build-id from it, if not some other identifier or simply looking for
"kallsyms.guest", for instance, in the current directory.

Reported-by: Mariano Pache <npache@redhat.com>
Tested-by: Mariano Pache <npache@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Cc: Ali Raza <alirazabhutta.10@gmail.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Mario <jmario@redhat.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Orran Krieger <okrieger@redhat.com>
Cc: Ramkumar Ramachandra <artagnon@gmail.com>
Cc: Yunlong Song <yunlong.song@huawei.com>
Link: https://lkml.kernel.org/n/tip-d54gj64rerlxcqsrod05biwn@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-script.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 520e5b6b9ef9..2f6232f1bfdc 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -3522,6 +3522,15 @@ int cmd_script(int argc, const char **argv)
"Time span of interest (start,stop)"),
OPT_BOOLEAN(0, "inline", &symbol_conf.inline_name,
"Show inline function"),
+ OPT_STRING(0, "guestmount", &symbol_conf.guestmount, "directory",
+ "guest mount directory under which every guest os"
+ " instance has a subdir"),
+ OPT_STRING(0, "guestvmlinux", &symbol_conf.default_guest_vmlinux_name,
+ "file", "file saving guest os vmlinux"),
+ OPT_STRING(0, "guestkallsyms", &symbol_conf.default_guest_kallsyms,
+ "file", "file saving guest os /proc/kallsyms"),
+ OPT_STRING(0, "guestmodules", &symbol_conf.default_guest_modules,
+ "file", "file saving guest os /proc/modules"),
OPT_END()
};
const char * const script_subcommands[] = { "record", "report", NULL };
@@ -3541,6 +3550,16 @@ int cmd_script(int argc, const char **argv)
argc = parse_options_subcommand(argc, argv, options, script_subcommands, script_usage,
PARSE_OPT_STOP_AT_NON_OPTION);

+ if (symbol_conf.guestmount ||
+ symbol_conf.default_guest_vmlinux_name ||
+ symbol_conf.default_guest_kallsyms ||
+ symbol_conf.default_guest_modules) {
+ /*
+ * Enable guest sample processing.
+ */
+ perf_guest = true;
+ }
+
data.path = input_name;
data.force = symbol_conf.force;

--
2.20.1