Re: [PATCH 2/8] perf metrics: fix parse errors in cascade lake metrics

[Ian Rogers]

On Wed, Apr 22, 2020 at 7:38 AM Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote:
>
> On Wed, Apr 22, 2020 at 12:48:03AM -0700, Ian Rogers wrote:
> > Remove over escaping with \\.
> > Remove extraneous if 1 if 0 == 1 else 0 else 0.
>
> So where do these parse errors happen exactly? Some earlier
> patches introduced them as regressions?

I'll work to track down a Fixes tag. I can repro the Skylakex errors
without the test in this series, by doing:

$ perf stat -M DRAM_Read_Latency sleep 1
Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument)
for event (cha/event=0x36\,uma
sk=0x21/).
/bin/dmesg | grep -i perf may provide additional information.

This was just the escaping issue. I'm less clear on the other cascade
lake issue, and it is a bit more work for me to test on cascade lake.
What is "if 1 if 0 == 1 else 0 else 0" trying to do? Perhaps hunting
for the Fixes will let me know, but it looks like a copy-paste error.

> The original metrics worked without parse errors as far as I know.

The skylake issue above repros on 5.2.17 and so it seems like it is
broken for a while. The test in this series will prevent this in the
future, but without this patch that test fails.

> If it fixes something earlier it would need Fixes: tags.

Working on it. Thanks for the input!

Ian

> -Andi