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ネットワーク インターフェイス名 (例: eth1 または eth2) に基づいて trace-cmd レポートを除外する方法はありますか?
trace-cmd レポート フィルターで "name" を EVENT_FIELD として使用しようとすると、何も得られません。
以下は私が使用したコマンドです

  [prap4test]$trace-cmd report -F 'net/netif_receive_skb:name=="eth1"'
  version = 6
  cpus=2
  [prap4test]$

しかし、「len」をEVENT_FIELDとして使用できました

[prap4test]$trace-cmd report -F 'net/netif_receive_skb'
version = 6
cpus=2
       trace-cmd-19979 [000] 499726.602505: netif_receive_skb:    dev=eth2 skbaddr=0xffff8800e9bb0e00 len=84
            sshd-21184 [000] 499726.603209: netif_receive_skb:    dev=eth1 skbaddr=0xffff8800e9bb0f00 len=52
       trace-cmd-19978 [000] 499727.809932: netif_receive_skb:    dev=eth2 skbaddr=0xffff8800e9bb5000 len=46
       trace-cmd-19979 [001] 499728.105372: netif_receive_skb:    dev=eth2 skbaddr=0xffff8800e753cc00 len=328
       trace-cmd-19978 [000] 499728.780571: netif_receive_skb:    dev=eth1 skbaddr=0xffff8800e9bb0700 len=100
[prap4test]$trace-cmd report -F 'net/netif_receive_skb:len >= 50'
version = 6
cpus=2
       trace-cmd-19979 [000] 499726.602505: netif_receive_skb:    dev=eth2 skbaddr=0xffff8800e9bb0e00 len=84
            sshd-21184 [000] 499726.603209: netif_receive_skb:    dev=eth1 skbaddr=0xffff8800e9bb0f00 len=52
       trace-cmd-19979 [001] 499728.105372: netif_receive_skb:    dev=eth2 skbaddr=0xffff8800e753cc00 len=328
       trace-cmd-19978 [000] 499728.780571: netif_receive_skb:    dev=eth1 skbaddr=0xffff8800e9bb0700 len=100

以下は、netif_receive_skb のイベント形式です。

name: netif_receive_skb
ID: 991
format:
        field:unsigned short common_type;       offset:0;       size:2; signed:0;
        field:unsigned char common_flags;       offset:2;       size:1; signed:0;
        field:unsigned char common_preempt_count;       offset:3;       size:1; signed:0;
        field:int common_pid;   offset:4;       size:4; signed:1;

        field:void * skbaddr;   offset:8;       size:8; signed:0;
        field:unsigned int len; offset:16;      size:4; signed:0;
        field:__data_loc char[] name;   offset:20;      size:4; signed:1;

print fmt: "dev=%s skbaddr=%p len=%u", __get_str(name), REC->skbaddr, REC->len

そして、trace-cmd-report で、次の詳細を見つけました

Note, the EVENT_FIELD is the field name as shown by an events format
(as displayed with *--events*), and not what is found in the output.
If the output shows "ID:foo" but the field that "foo" belongs to was
called "name" in the event format, then "name" must be used in the filter.
The same is true about values. If the value that is displayed is converted
by to a string symbol, the filter checks the original value and not the
value displayed. For example, to filter on all tasks that were in the
running state at a context switch:

    -F 'sched/sched_switch : prev_state==0'

Although the output displays 'R', having 'prev_stat=="R"' will not work.

要するに、「名前」EVENT_FIELDに基づいて除外するコマンドを知りたい

前もってありがとう、
prap4search

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1 に答える 1

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これは確かに trace-cmd のバグです。
修正として、Steven Rostedt (trace-cmd の作成者) から次のパッチを入手しました。

diff --git a/parse-filter.c b/parse-filter.c
index c2fd26f..8e302c4 100644
--- a/parse-filter.c
+++ b/parse-filter.c
@@ -1880,17 +1880,25 @@ static const char *get_field_str(struct filter_arg *arg, struct pevent_record *r
    struct pevent *pevent;
    unsigned long long addr;
    const char *val = NULL;
+    unsigned int size;
    char hex[64];

    /* If the field is not a string convert it */
    if (arg->str.field->flags & FIELD_IS_STRING) {
        val = record->data + arg->str.field->offset;
+        size = arg->str.field->size;
+
+        if (arg->str.field->flags & FIELD_IS_DYNAMIC) {
+            addr = *(unsigned int *)val;
+            val = record->data + (addr & 0xffff);
+            size = addr >> 16;
+        }

        /*
        * We need to copy the data since we can't be sure the field
        * is null terminated.
        */
-        if (*(val + arg->str.field->size - 1)) {
+        if (*(val + size - 1)) {
            /* copy it */
            memcpy(arg->str.buffer, val, arg->str.field->size);
            /* the buffer is already NULL terminated */

パッチを適用した後、インターフェイス名を使用して除外できます

[prap4test]$../trace-cmd/trace-cmd report -F 'net/netif_receive_skb:name=="eth1"'
cpus=2
       trace-cmd-1108  [000] 1111798.397704: netif_receive_skb:    dev=eth1 skbaddr=0xffff8800e9f5ee00 len=52
       trace-cmd-1108  [000] 1111798.428998: netif_receive_skb:    dev=eth1 skbaddr=0xffff8800e867b400 len=392
       trace-cmd-1108  [000] 1111798.989447: netif_receive_skb:    dev=eth1 skbaddr=0xffff8800e743ed00 len=46
       trace-cmd-1108  [000] 1111799.450838: netif_receive_skb:    dev=eth1 skbaddr=0xffff8800eab94b00 len=576
       trace-cmd-1108  [000] 1111799.549737: netif_receive_skb:    dev=eth1 skbaddr=0xffff8800eab94700 len=576
       trace-cmd-1108  [000] 1111800.263439: netif_receive_skb:    dev=eth1 skbaddr=0xffff8800e87c4e00 len=100
于 2017-07-06T21:29:29.387 に答える