Hi Leo,

On 06/10/2021 10:51, Leo Yan wrote:

On Wed, Oct 06, 2021 at 10:35:20AM +0100, German Gomez wrote:

[...]

quoted

quoted

So simply say, I think the head pointer monotonically increasing is
the right thing to do in Arm SPE driver.

I will talk to James about how we can proceed on this.

Thanks!

I took this offline with James and, though it looks possible to patch
the SPE driver to have a monotonically increasing head pointer in order
to simplify the handling in the perf tool, it could be a breaking change
for users of the perf_event_open syscall that currently rely on the way
it works now.

An alternative way we considered to simplify the patch is to change the
logic inside the find_snapshot callback so that it records the entire
contents of the aux buffer every time.

What do you think?

Many thanks,
German