On 3 Nov 2021, at 6:26, Y Song wrote:
> On Tue, Nov 2, 2021 at 7:31 AM Eelco Chaudron <[email protected]> wrote:
>>
>> [Edited Message Follows]
>>
>> On Tue, Nov 2, 2021 at 03:24 PM, Eelco Chaudron wrote:
>>
>> Hi,
>>
>> Was wondering if there is a way to count the number of times
>> map.ringbuf_reserve() fails for a BPF_RINGBUF_OUTPUT buffer?
>>
>> This way I can get notified in userspace that I have missed events, and
>> might need to increase the buffer size.
>>
>> Cheers,
>>
>> Eelco
>>
>> Thought I added the #bcc tag but I no longer see it :( So just in case, it's
>> not clear, this is with BCC.
>
> You can check return value of map.ringbuf_reserve(). If the
> reservation failed, you can notify user space through map, another
> side channel ringbuf, perf buf, etc. Depending on your program type
> and program running context, you might be able to use
> bpf_send_signal() helper to send a signal to the *current* process.
Thanks, I was looking at BCC to solve this in the wrappers, but you are right,
as simple BPF_TABLE() solved it.
//Eelco
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