Re: [PATCH 13/15] perf stat: Fix JSON output in metric-only mode

[Namhyung Kim]

Hello,

On Thu, Dec 1, 2022 at 4:56 PM Wang, Weilin <weilin.wang@xxxxxxxxx> wrote:
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> Hi Namhyung,
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>
> I encountered an issue with the metric json output, which I think might be related to this commit.
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> This is one of the commands I tried:
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> ./perf stat -M memory_bandwidth_total,memory_bandwidth_read,memory_bandwidth_write -a -j -- sleep 1
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> Output before this commit:
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> ====================================================
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> {"counter-value" : "1117309.000000", "unit" : "", "event" : "UNC_M_CAS_COUNT.RD", "event-runtime" : 8017286783, "pcnt-running" : 100.00, "metric-value" : 124.961911, "metric-unit" : "MB/s  memory_bandwidth_read"} {"metric-value" : 237.237504, "metric-unit" : "MB/s  memory_bandwidth_total"} {"counter-value" : "1004052.000000", "unit" : "", "event" : "UNC_M_CAS_COUNT.WR", "event-runtime" : 8017286783, "pcnt-running" : 100.00, "metric-value" : 112.275593, "metric-unit" : "MB/s  memory_bandwidth_write"} {"counter-value" : "1002140370.000000", "unit" : "ns", "event" : "duration_time", "event-runtime" : 1002140370, "pcnt-running" : 100.00, "metric-value" : 0.000000, "metric-unit" : "(null)"}
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> ====================================================
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> Output after this commit:
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> ====================================================
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> {"counter-value" : "1374098.000000", "unit" : "", "event" : "UNC_M_CAS_COUNT.RD", "event-runtime" : 8016491003, "pcnt-running" : 100.00, "metric-value" : 153.660738, "metric-unit" : "MB/s  memory_bandwidth_read"} "metric-value" : 300.338968, "metric-unit" : "MB/s  memory_bandwidth_total"} {"counter-value" : "1311710.000000", "unit" : "", "event" : "UNC_M_CAS_COUNT.WR", "event-runtime" : 8016491003, "pcnt-running" : 100.00, "metric-value" : 146.678229, "metric-unit" : "MB/s  memory_bandwidth_write"} {"counter-value" : "1002037512.000000", "unit" : "ns", "event" : "duration_time", "event-runtime" : 1002037512, "pcnt-running" : 100.00, "metric-value" : 0.000000, "metric-unit" : "(null)"}
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> ====================================================
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> The second set of output is missing a "{" on the second line. Looks like it happens when I collect two related metrics together. Another example is:
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> ./perf stat -M memory_bandwidth_total,memory_bandwidth_read,memory_bandwidth_write,L3_Cache_Fill_BW_1T,L3_Cache_Fill_BW -a -j -- sleep 1
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> {"counter-value" : "944204.000000", "unit" : "", "event" : "UNC_M_CAS_COUNT.RD", "event-runtime" : 8033937053, "pcnt-running" : 100.00, "metric-value" : 105.369994, "metric-unit" : "MB/s  memory_bandwidth_read"} "metric-value" : 210.592807, "metric-unit" : "MB/s  memory_bandwidth_total"} {"counter-value" : "942679.000000", "unit" : "", "event" : "UNC_M_CAS_COUNT.WR", "event-runtime" : 8033937053, "pcnt-running" : 100.00, "metric-value" : 105.222813, "metric-unit" : "MB/s  memory_bandwidth_write"} {"counter-value" : "1004471458.000000", "unit" : "ns", "event" : "duration_time", "event-runtime" : 1004471458, "pcnt-running" : 100.00, "metric-value" : 0.000000, "metric-unit" : "(null)"} {"counter-value" : "184675.000000", "unit" : "", "event" : "LONGEST_LAT_CACHE.MISS", "event-runtime" : 88387319917, "pcnt-running" : 100.00, "metric-value" : 0.011767, "metric-unit" : "L3_Cache_Fill_BW_1T"} "metric-value" : 0.011767, "metric-unit" : "L3_Cache_Fill_BW"} {"counter-value" : "1004471458.000000", "unit" : "ns", "event" : "duration_time", "event-runtime" : 1004471458, "pcnt-running" : 100.00, "metric-value" : 0.000000, "metric-unit" : "(null)"}

Thanks for your report.  It seems it misses the open bracket when the metric
produces more than one values.  I think new_line_json() should have it.
Will send the fix soon.

Thanks,
Namhyung