Re: [PATCH v3 1/3] perf: add PERF_RECORD_NAMESPACES to include namespaces related info

From: Hari Bathini
Date: Tue Dec 13 2016 - 13:47:46 EST


Hi Eric,


On Monday 12 December 2016 11:57 PM, Eric W. Biederman wrote:
Hari Bathini <hbathini@xxxxxxxxxxxxxxxxxx> writes:

With the advert of container technologies like docker, that depend
on namespaces for isolation, there is a need for tracing support for
namespaces. This patch introduces new PERF_RECORD_NAMESPACES event
for tracing based on namespaces related info.
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index c66a485..2a48fc6 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -344,7 +344,8 @@ struct perf_event_attr {
use_clockid : 1, /* use @clockid for time fields */
context_switch : 1, /* context switch data */
write_backward : 1, /* Write ring buffer from end to beginning */
- __reserved_1 : 36;
+ namespaces : 1, /* include namespaces data */
+ __reserved_1 : 35;
union {
__u32 wakeup_events; /* wakeup every n events */
@@ -610,6 +611,18 @@ struct perf_event_header {
__u16 size;
};
+enum {
+ NET_NS_INDEX = 0,
+ UTS_NS_INDEX = 1,
+ IPC_NS_INDEX = 2,
+ PID_NS_INDEX = 3,
+ USER_NS_INDEX = 4,
+ MNT_NS_INDEX = 5,
+ CGROUP_NS_INDEX = 6,
+
+ NAMESPACES_MAX, /* maximum available namespaces */
+};
+
enum perf_event_type {
/*
@@ -862,6 +875,18 @@ enum perf_event_type {
*/
PERF_RECORD_SWITCH_CPU_WIDE = 15,
+ /*
+ * struct {
+ * struct perf_event_header header;
+ *
+ * u32 pid, tid;
+ * u64 dev_num;
+ * u64 inode_num[NAMESPACES_MAX];
There needs to be one device number per inode. While it is true that
today the device number is always the same. That is not necessarily so.
I reserve the right to have the device number vary per namespace
so that I don't need to implement a namespace of namespaces.

These are st_dev and st_ino of the inode for the namespace.

Do you mean..

st_dev = encode_dev(inode->i_sb->s_dev); ?
st_ino = inode->i_ino; ?

Thanks
Hari