Command perf kvm diff is used to diff perf.data.host and
perf.data.guest by default currently. But it is not a good
default behavior.
Example:
# perf kvm --guestkallsyms /home/kallsyms --guestmodules /home/modules
record -a sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.669 MB perf.data.guest (~29207
samples) ]
# perf kvm --guestkallsyms /home/kallsyms --guestmodules /home/modules
record -a sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.669 MB perf.data.guest (~29207
samples) ]
# perf kvm --guestkallsyms /home/kallsyms --guestmodules /home/modules
diff
failed to open perf.data.host: No such file or directory
Failed to open perf.data.host
We should keep the style of 'perf kvm diff' same with 'perf diff'.
It is used to diff files with same type but captured in different
times, perf.data and perf.data.old. So we need to make perf kvm diff
to diff perf.data.guest and perf.data.guest.old as a default behavior.
What's worse, as we have changed the behaviors of perf kvm record,
we can not get a perf.data.host easily. We have to use a --no-guest
to get a perf.data.host, it means we use perf.data.host as a default
input in 'perf kvm diff' is an odd design.
This patch remove the hard coding of default filenames in builtin-diff.c,
and generate the suitable filename from current options in perf kvm diff
command. It makes the default behavior of perf kvm diff be more valuable.
Verification:
# perf kvm --guestkallsyms /home/kallsyms --guestmodules /home/modules
record -a sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.669 MB perf.data.guest (~29207
samples) ]
# perf kvm --guestkallsyms /home/kallsyms --guestmodules /home/modules
record -a sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.669 MB perf.data.guest (~29207
samples) ]
# perf kvm --guestkallsyms /home/kallsyms --guestmodules /home/modules
diff
# Event 'cycles'
#
# Baseline Delta Shared Object
Symbol
# ........ ....... .......................
.......................................
#
92.00% [guest.kernel.kallsyms] [g] rb_insert_color
7.51% [guest.kernel.kallsyms] [g]
smp_apic_timer_interrupt
0.48% +0.60% [guest.kernel.kallsyms] [g] apic_timer_interrupt
+16.35% [guest.kernel.kallsyms] [g] kvm_clock_get_cycles
+82.56% [guest.kernel.kallsyms] [g]
irqtime_account_process_tick.isra.2
Signed-off-by: Dongsheng Yang <yangds.f...@cn.fujitsu.com>
---
tools/perf/builtin-diff.c | 25 +++++++++++++++++++++++--
1 file changed, 23 insertions(+), 2 deletions(-)
diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 2a85cc9..a1d59d8 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -17,6 +17,7 @@
#include "util/symbol.h"
#include "util/util.h"
#include "util/data.h"
+#include "linux/string.h"
#include <stdlib.h>
#include <math.h>
@@ -1001,8 +1002,28 @@ static int data_init(int argc, const char **argv)
use_default = false;
}
} else if (perf_guest) {
- defaults[0] = "perf.data.host";
- defaults[1] = "perf.data.guest";
+ char *file_name;
+ int len, ret;
+
+ file_name = strdup(get_filename_for_perf_kvm());
+ if (!file_name) {
+ pr_err("Failed to allocate memory for filename\n");
+ return -ENOMEM;
+ }
+
+ defaults[0] = strdup(file_name);
+ if (!defaults[0]) {
+ pr_err("Failed to allocate memory for defaults[0]\n");
+ return -ENOMEM;
+ }
+
+ len = strlen(file_name);
+ ret = str_append(&file_name, &len, ".old");
+ if (ret) {
+ pr_err("Failed to allocate memory for defaults[1]\n");
+ return -ENOMEM;
+ }
+ defaults[1] = file_name;
}
if (sort_compute >= (unsigned int) data__files_cnt) {
--
1.8.2.1
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