On Thu, Dec 5, 2013 at 8:11 AM, Frank Ch. Eigler <f...@redhat.com> wrote:
>
> ast wrote:
>
>>>[...]
>> Did simple ktap test with 1M alloc_skb/kfree_skb toy test from earlier email:
>> trace skb:kfree_skb {
>> if (arg2 == 0x100) {
>> printf("%x %x\n", arg1, arg2)
>> }
>> }
>> [...]
>
> For reference, you might try putting systemtap into the performance
> comparison matrix too:
>
> # stap -e 'probe kernel.trace("kfree_skb") {
> if ($location == 0x100 /* || $location == 0x200 etc. */ ) {
> printf("%x %x\n", $skb, $location)
> }
> }'
stap with one 'if': 1M skb alloc/free 200696 (usecs)
stap with 10 'if': 1M skb alloc/free 202135 (usecs)
so systemtap entry overhead is a bit higher than bpf and extra if-s
show the same progression as expected.
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