On Tue, 18 Nov 2014 14:01:06 +0000, Kan Liang wrote:
>> On Fri, 14 Nov 2014 08:44:12 -0500, kan liang wrote:
>> > + /* LBR only affects the user callchain */
>> > + if (i != chain_nr) {
>> > + struct branch_stack *lbr_stack = sample-
>> >branch_stack;
>> > + int lbr_nr = lbr_stack->nr;
>> > + /*
>> > + * LBR callstack can only get user call chain.
>> > + * The mix_chain_nr is kernel call chain
>> > + * number plus LBR user call chain number.
>> > + * i is kernel call chain number,
>> > + * 1 is PERF_CONTEXT_USER,
>> > + * lbr_nr + 1 is the user call chain number.
>> > + * For details, please refer to the comments
>> > + * in callchain__printf
>> > + */
>> > + int mix_chain_nr = i + 1 + lbr_nr + 1;
>> > +
>> > + if (mix_chain_nr > PERF_MAX_STACK_DEPTH) {
>> > + pr_warning("corrupted callchain.
>> skipping...\n");
>> > + return 0;
>> > + }
>>
>> I'm not sure whether this is really a corrupted callchain. If a single
>> chain is
>> greater than the max it should be corrupted, but we're now summing up
>> with other values..
>>
>> What about checking callchain_nr and lbr_nr separately or mix_nr with
>> 2*max?
>
> The lbr_nr max is 16. I will change it to max+16.
Shouldn't it be 18 (16 + 1 + 1) at least?
Thanks,
Namhyung
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