linux-kernel - Re: [PATCH] perf test: Test case 27 fails on s390 and non-x86 platforms

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Message-ID: <abcf63c1-8a15-14af-b449-77a943c94121@linux.intel.com>
Date:   Tue, 2 Mar 2021 09:03:52 -0500
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Thomas Richter <tmricht@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        acme@...nel.org
Cc:     svens@...ux.ibm.com, gor@...ux.ibm.com, sumanthk@...ux.ibm.com,
        heiko.carstens@...ibm.com,
        Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
Subject: Re: [PATCH] perf test: Test case 27 fails on s390 and non-x86
 platforms


+ Athira Rajeev

On 3/2/2021 8:31 AM, Thomas Richter wrote:
> Executing perf test 27 fails on s390:
>   [root@...lp46 perf]# ./perf test -Fv 27
>   27: Sample parsing
>   --- start ---
>   ---- end ----
>   Sample parsing: FAILED!
>   [root@...lp46 perf]#
> 
> The root cause is
> commit c7444297fd3769 ("perf test: Support PERF_SAMPLE_WEIGHT_STRUCT")
> This commit introduced a test case for PERF_SAMPLE_WEIGHT_STRUCT
> but does not adjust non-x86 weak linkage functions.
> 
> The error is in test__sample_parsing() --> do_test()
> Function do_test() defines two structures of type struct perf_sample named
> sample and sample_out. The first sets member sample.ins_lat = 117
> 
> Structure sample_out is constructed dynamically using functions
> perf_event__synthesize_sample() and evsel__parse_sample().
> Both functions have an x86 specific function version which sets member
> ins_lat. The weak common functions do not set member ins_lat.
>

I don't think Power supports the instruction latency. As a request from 
Athira Rajeev, I moved the PERF_SAMPLE_WEIGHT_STRUCT to the X86 specific 
codes.
https://lore.kernel.org/lkml/D97FEF4F-DD88-4760-885E-9A6161A9B48B@linux.vnet.ibm.com/
https://lore.kernel.org/lkml/1612540912-6562-1-git-send-email-kan.liang@linux.intel.com/

I don't think we want to add the ins_lat back in the weak common functions.

Could you please update the perf test and don't apply the 
PERF_SAMPLE_WEIGHT_STRUCT for the non-X86 platform?


> Later in function samples_same() both data in variable sample and sample_out
> are compared. The comparison fails because sample.ins_lat is 117
> and samples_out.ins_lat is 0, the weak functions never set member ins_lat.
> 
> Output after:
>   [root@...lp46 perf]# ./perf test -Fv 27
>   27: Sample parsing
>   --- start ---
>   ---- end ----
>   Sample parsing: Ok
> [root@...lp46 perf]#
> 
> Fixes:
> commit c7444297fd3769 ("perf test: Support PERF_SAMPLE_WEIGHT_STRUCT")

I think the regression should start from
commit fbefe9c2f87f ("perf tools: Support arch specific 
PERF_SAMPLE_WEIGHT_STRUCT processing")


Thanks,
Kan
> 
> Signed-off-by: Thomas Richter <tmricht@...ux.ibm.com>
> ---
>   tools/perf/util/evsel.c            | 8 +++++---
>   tools/perf/util/synthetic-events.c | 6 +++++-
>   2 files changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 1bf76864c4f2..c9efed5c173d 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -2106,10 +2106,12 @@ perf_event__check_size(union perf_event *event, unsigned int sample_size)
>   }
>   
>   void __weak arch_perf_parse_sample_weight(struct perf_sample *data,
> -					  const __u64 *array,
> -					  u64 type __maybe_unused)
> +					  const __u64 *array, u64 type)
>   {
> -	data->weight = *array;
> +	if (type & PERF_SAMPLE_WEIGHT)
> +		data->weight = *array & 0xffffffff;
> +	if (type & PERF_SAMPLE_WEIGHT_STRUCT)
> +		data->ins_lat = (*array >> 32) & 0xffff;
>   }
>   
>   int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
> diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
> index b698046ec2db..af7ecbc57cbe 100644
> --- a/tools/perf/util/synthetic-events.c
> +++ b/tools/perf/util/synthetic-events.c
> @@ -1507,9 +1507,13 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
>   }
>   
>   void __weak arch_perf_synthesize_sample_weight(const struct perf_sample *data,
> -					       __u64 *array, u64 type __maybe_unused)
> +					       __u64 *array, u64 type)
>   {
>   	*array = data->weight;
> +	if (type & PERF_SAMPLE_WEIGHT_STRUCT) {
> +		*array &= 0xffffffff;
> +		*array |= ((u64)data->ins_lat << 32);
> +	}
>   }
>   
>   int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
>