linux-kernel - Re: [PATCH v3] perf: map pages in advance

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Message-ID: <74fd8a75-66c6-40a8-9ec3-d7aa74469755@intel.com>
Date: Fri, 20 Dec 2024 11:36:15 -0800
From: "Chen, Zide" <zide.chen@...el.com>
To: David Hildenbrand <david@...hat.com>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
 Adrian Hunter <adrian.hunter@...el.com>,
 Kan Liang <kan.liang@...ux.intel.com>, linux-perf-users@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 Matthew Wilcox <willy@...radead.org>, Yi Lai <yi1.lai@...ux.intel.com>
Subject: Re: [PATCH v3] perf: map pages in advance



On 12/20/2024 1:56 AM, David Hildenbrand wrote:
> On 20.12.24 10:31, Lorenzo Stoakes wrote:
>> On Thu, Dec 19, 2024 at 01:17:44PM -0800, Chen, Zide wrote:
>>
>>> With this patch, it seems perf tool has some problems in capturing the
>>> kernel data with Intel PT.
>>>
>>> Running the following commands, the size of perf.data is very small, and
>>> perf script can't find any valid records.
>>>
>>> perf record -e intel_pt//u -- /bin/ls
>>> perf script --insn-trace
>>>
>>>
>>
>> Hi,
>>
>> I'm on leave (and should really go back to relaxing :>), returning on 2nd
>> Jan so can't really dig into this.
>>
>> But I tried it on my intel box and it 'works on my machine' with and
>> without patch with commands provided, so I'm not sure this is actually a
>> product of this change (which shouldn't impact this).
> 
> Zide Chen, can you try with and without this patch to see if it
> introduces the issue?

Yes, I re-did the test on a SPR server, and the result is same. Without
the patch, it went well; But with it, "perf script --insn-trace" doesn't
show valid records.

This time I tested it on the clean 6.13-rc1 tag, base commit
40384c840ea1944d7c5a392e8975ed088ecf0b37

Also, with this patch, running tools/perf/tests/shell/test_intel_pt.sh:

Error:
The - data has no samples!