linux-kernel - Re: [PATCH v1 1/2] perf auxtrace: Add 'T' itrace option for timestamp trace

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <6fc8bc4c-abc3-45d5-a8c8-045f91adfebf@intel.com>
Date:   Tue, 7 Nov 2023 12:16:25 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Leo Yan <leo.yan@...aro.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        James Clark <james.clark@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        John Garry <john.g.garry@...cle.com>,
        Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>, coresight@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] perf auxtrace: Add 'T' itrace option for timestamp
 trace

On 7/11/23 11:48, Leo Yan wrote:
> Hi Adrian,
> 
> On Tue, Nov 07, 2023 at 09:19:10AM +0200, Adrian Hunter wrote:
>> On 6/11/23 23:52, Arnaldo Carvalho de Melo wrote:
>>> Em Thu, Oct 19, 2023 at 01:47:15PM +0300, Adrian Hunter escreveu:
>>>> On 14/10/23 10:45, Leo Yan wrote:
>>>>> An AUX trace can contain timestamp, but in some situations, the hardware
>>>>> trace module (e.g. Arm CoreSight) cannot decide the traced timestamp is
>>>>> the same source with CPU's time, thus the decoder can not use the
>>>>> timestamp trace for samples.
>>>>>
>>>>> This patch introduces 'T' itrace option. If users know the platforms
>>>>
>>>> "If users know" <- how would users know?  Could the kernel
>>>> or tools also figure it out?
>>>
>>> Adrian, I'm trying to go all the outstanding patches, do you still have
>>> any issues with this series?
>>
>> No, although the question wasn't actually answered.  I presume users
>> just have to try the 'T' option and see if it helps.
> 
> Sometimes, users are software developers in SoC companies, they can
> know well for the hardware design but are confused why current
> implementation cannot use timestamp trace.  This is the main reason
> I sent this patch set.
> 
> An example hardware platform is DB410c [1], we know its CoreSight can
> support timestamp trace, but if without this adding option 'T', we
> have no chance to use it due to it its CPU arch is prior to Armv8.4.

perf config might be better than an itrace option, but you decide.

> 
> @Arnaldo, since James gave comments in his replying, I will respin new
> patch set and send out.  Thanks for popping up this patch set!
> 
> Leo
> 
> [1] https://developer.qualcomm.com/hardware/dragonboard-410c