linux-kernel - Re: [PATCH drivers/perf: hisi: 1/2] drivers/perf: hisi: hns3: default use hardware event 0 as group leader event.

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Message-ID: <20230821115820.GA19617@willie-the-truck>
Date:   Mon, 21 Aug 2023 12:58:20 +0100
From:   Will Deacon <will@...nel.org>
To:     Jijie Shao <shaojijie@...wei.com>
Cc:     jonathan.cameron@...wei.com, mark.rutland@....com,
        chenhao418@...wei.com, shenjian15@...wei.com,
        wangjie125@...wei.com, liuyonglong@...wei.com,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH drivers/perf: hisi: 1/2] drivers/perf: hisi: hns3:
 default use hardware event 0 as group leader event.

On Wed, Aug 16, 2023 at 05:46:18PM +0800, Jijie Shao wrote:
> From: Hao Chen <chenhao418@...wei.com>
> 
> For hns3 pmu events, we use command as below before:
> perf stat -g -e hns3_pmu_sicl_0/config=0x00105,global=1/
> -e hns3_pmu_sicl_0/config=0x10105,global=1/ -I 1000
> 
> We want to use -g parameter to make 0x00105 event and 0x10105 event
> share a hardware event, but for kernel 6.2, 'commit 5f8f95673f68
> ("perf evlist: Remove group option.")' remove -g parameter.
> 
> So add this patch to set default related event idx as 0 to share
> the first hardware event.

Hmm, but the change cited above is a userspace change so I don't think
we should be making driver-side changes for that. Furthermore, the commit
message there suggests that you should be using a different syntax,
introduced by 89efb029502d ("perf tools: Add support to parse event
group syntax") (which describes the grammer and has some examples too).

Will