Messages in this thread | | | Subject | Re: [PATCH v7 2/2] drivers/perf: hisi: Add driver for HiSilicon PCIe PMU | From | John Garry <> | Date | Mon, 28 Jun 2021 13:11:33 +0100 |
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On 28/06/2021 11:49, liuqi (BA) wrote: >>> Hardware counter and ext_counter work together for bandwidth, latency, >>> bus utilization and buffer occupancy events. For example, for latency >>> events(idx = 0x10), counter counts total delay cycles and ext_counter >>> counts PCIe packets number. >>> >>> As we don't want PMU driver to process these two data, "delay cycles" >>> can be treated as an event(id = 0x10), "packets number" as another event >>> (id = 0x10 << 8), and driver could export these data separately. >>> >>> if the user want to calculate latency of rx memory read, they should: >>> ./perf stat -v -e '{hisi_pcieX/event=0x10, >>> subevent=0x01/,hisi_pcieX/event=0x0400, subevent=0x01/ >>> >>> and for bandwidth event: >>> ./perf stat -v -e '{hisi_pcieX/event=0x4, >>> subevent=0x02/,hisi_pcieX/event=0x1000, subevent=0x02/ > Hi John, >> I would suggest supporting a perf metric for this then, which would be >> like: >> >> { >> "BriefDescription": "Latency for inbound traffic...", >> "MetricName": "hisi_pcie_lat_rx_mrd", >> "MetricExpr": "hisi_pcieX@event\\=0x4@subevent\\=0x02 \ >> hisi_pcieX@event\\=0x1000@subevent\\=0x02 \", >> "Unit": "hisi_pci", >> "Compat": "v1" >> }, >> >> (syntax may be incorrect - illustration only) >> > yes, we could add these metrics in json file, thanks.
The syntax is actually like: "MetricExpr": "hisi_pcieX@event\\=0x4\\,subevent\\=0x2@ / hisi_pcieX@event\\=0x1000\\,subevent\\=0x2@",
>>> Then the value in HISI_PCIE_CNT and HISI_PCIE_EXT_CNT returned >>> separately, and userspace could do the calculation. >> But I am still curious about lat_rx_mrd and the other events which we >> continue to advertise. They don't really provide latency or bandwidth on >> their own, but only half the necessary data. So I doubt their purpose. >> > So how about changing the event name to show the real purpose of this > event, like changing "bw_rx_mrd" to "flux_rx_mrd", and changing > "lat_rx_mrd" to "delay_rx_mrd"?
eh, I suppose you could, but I am not sure of the value. However I assume that the driver will detect and reject invalid or nonsense combinations of events if you did want this.
Thanks, John
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