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
