Using poll(2) on trace files

[Aryeh Weinreb]

Answering my own question, please correct me if I'm wrong.
With relayfs, poll is only notified when sub-buffer bounders are crossed.
So if I want to stream data from the buffer, I need either wait for the
first sub-buffer to fill or call read periodically non-blocking.


On Tue, May 15, 2018 at 2:27 PM, Aryeh Weinreb <aryehweinreb@gmail.com>
wrote:

> Hi,
>
> I would like to process the systemtap trace files in userspace without
> writing to disk.
> I built the kernel module with stap -p4 then loaded it with staprun -L.
> I would like to use poll(2) on the trace0 file to wait for data but I am
> not getting POLLIN set even though there is data I can read from the file.
> What am I missing?
>
> Thanks,
> Aryeh
>