Messages in this thread | | | From | Menglong Dong <> | Date | Tue, 16 Nov 2021 10:27:41 +0800 | Subject | Re: [PATCH net-next 0/2] net: snmp: tracepoint support for snmp |
| |
Hello~
On Fri, Nov 12, 2021 at 10:31 PM Steven Rostedt <rostedt@goodmis.org> wrote: > > On Fri, 12 Nov 2021 14:42:23 +0800 > Menglong Dong <menglong8.dong@gmail.com> wrote: > > > What's more, I have also realized another version: create tracepoint for every > > statistics type, such as snmp_udp_incsumerrors, snmp_udp_rcvbuferrors, etc. > > This can solve performance issue, as users can enable part of them, which > > may be triggered not frequently. However, too many tracepoint are created, and > > I think it may be not applicable. > > If possible, it would be great to have a single tracepoint to handle all > statistics (not sure what data it will be having). Or at least break it > down to one tracepoint per group of statistics. > > There's two approaches that can be taken. > > 1) Create a DECLARE_EVENT_CLASS() template that the group of tracepoints > use, and then create a DEFINE_EVENT() for each one. This will create a > separate trace event for each stat. Most the footprint of a trace event is > in the CLASS portion, so having a single class helps keep the size overhead > down. >
In fact, I think I'm using the first idea. I defined the DEFINE_SNMP_EVENT() in https://lore.kernel.org/all/20211111133530.2156478-2-imagedong@tencent.com/, which is used to create the tracepoint for each group. And I plan to create tracepoint by protocols. such as: events/snmp/snmp_udp, events/snmp/snmp_tcp, events/snmp/snmp_icmp, etc. And every trace event have a type field, which is used to simply filter by statistics type:
+DECLARE_EVENT_CLASS(snmp_template, + + TP_PROTO(struct sk_buff *skb, int field, int val), + + TP_ARGS(skb, field, val), + + TP_STRUCT__entry( + __field(void *, skbaddr) + __field(int, field) + __field(int, val) + ), + + TP_fast_assign( + __entry->skbaddr = skb; + __entry->field = field; + __entry->val = val; + ), + + TP_printk("skbaddr=%p, field=%d, val=%d", __entry->skbaddr, + __entry->field, __entry->val) +); + +#define DEFINE_SNMP_EVENT(proto) \ +DEFINE_EVENT(snmp_template, snmp_##proto, \ + TP_PROTO(struct sk_buff *skb, int field, int val), \ + TP_ARGS(skb, field, val) \ +)
I think using a single trace event may have performance impact?
I will post the complete patch series after netdev opens.
Thanks! Menglong Dong
> 2) Just use a single trace event for all stats in a group, but perhaps have > a type field for each to use. That way it can be easy to filter on a set of > stats to trace. > > -- Steve
| |