On Tue, Jun 15, 2021 at 04:57:09PM +0800, liuqi (BA) wrote:
> On 2021/6/12 0:23, Will Deacon wrote:
> > On Mon, May 31, 2021 at 09:32:31PM +0800, Qi Liu wrote:
> > > PCIe PMU Root Complex Integrated End Point(RCiEP) device is supported
> > > to sample bandwidth, latency, buffer occupation etc.
> > >
> > > Each PMU RCiEP device monitors multiple Root Ports, and each RCiEP is
> > > registered as a PMU in /sys/bus/event_source/devices, so users can
> > > select target PMU, and use filter to do further sets.
> > >
> > > Filtering options contains:
> > > event - select the event.
> > > subevent - select the subevent.
> > > port - select target Root Ports. Information of Root Ports
> > > are shown under sysfs.
> > > bdf - select requester_id of target EP device.
> > > trig_len - set trigger condition for starting event statistics.
> > > trigger_mode - set trigger mode. 0 means starting to statistic when
> > > bigger than trigger condition, and 1 means smaller.
> > > thr_len - set threshold for statistics.
> > > thr_mode - set threshold mode. 0 means count when bigger than
> > > threshold, and 1 means smaller.
> > >
> > > Reviewed-by: John Garry <john.garry@xxxxxxxxxx>
> > > Signed-off-by: Qi Liu <liuqi115@xxxxxxxxxx>
> > > ---
> > > MAINTAINERS | 6 +
> > > drivers/perf/Kconfig | 2 +
> > > drivers/perf/Makefile | 1 +
> > > drivers/perf/pci/Kconfig | 16 +
> > > drivers/perf/pci/Makefile | 2 +
> > > drivers/perf/pci/hisilicon/Makefile | 3 +
> > > drivers/perf/pci/hisilicon/hisi_pcie_pmu.c | 1019 ++++++++++++++++++++++++++++
> >
> > Can we keep this under drivers/perf/hisilicon/ please? I don't see the
> > need to create a 'pci' directory here.
> >
> So how about drivers/perf/hisilicon/pci? as hisi_pcie_pmu.c do not use
> hisi_uncore_pmu framework.
That's up to you. As long as it's _somewhere_ under drivers/perf/hisilicon/,
then I'm not too fussed.
> > > +static void hisi_pcie_parse_reg_value(struct hisi_pcie_pmu *pcie_pmu,
> > > + u32 reg_off, u16 *arg0, u16 *arg1)
> > > +{
> > > + u32 val = readl(pcie_pmu->base + reg_off);
> > > +
> > > + *arg0 = val & 0xffff;
> > > + *arg1 = (val & 0xffff0000) >> 16;
> > > +}
> >
> > Define a new type for the pair of values and return that directly?
> >
> Sorry, I'm not sure about how to fix this, do you mean add a union like
> this?
> union reg_val {
> struct {
> u16 arg0;
> u16 arg1;
> }
> u32 val;
> }
I was just thinking along the lines of:
struct hisi_pcie_reg_pair {
u16 lo;
u16 hi;
};
static struct hisi_pcie_reg_pair
hisi_pcie_parse_reg_value(struct hisi_pcie_pmu *pcie_pmum u32 reg_off)
{
u32 val = readl_relaxed(pcie_pmu->base + reg_off);
struct hisi_pcie_reg_pair regs = {
.lo = val,
.hi = val >> 16,
};
return regs;
}
Does that work?
> > > +/*
> > > + * The bandwidth, latency, bus utilization and buffer occupancy features are
> > > + * calculated from data in HISI_PCIE_CNT and extended data in HISI_PCIE_EXT_CNT.
> > > + * Other features are obtained only by HISI_PCIE_CNT.
> > > + * So data and data_ext are processed in this function to get performanace
> > > + * value like, bandwidth, latency, etc.
> > > + */
> > > +static u64 hisi_pcie_pmu_get_performance(struct perf_event *event, u64 data,
> > > + u64 data_ext)
> > > +{
> > > +#define CONVERT_DW_TO_BYTE(x) (sizeof(u32) * (x))
> >
> > I don't know what a "DW" is, but this macro adds nothing...
>
> DW means double words, and 1DW = 4Bytes, value in hardware counter means DW
> so I wanna change it into Byte.
> So how about using 4*data here and adding code comment to explain it.
Just remove the macro and replace it's single user with sizeof(u32) * x
> > > + /* Process data to set unit of latency as "us". */
> > > + if (is_latency_event(idx))
> > > + return div64_u64(data * us_per_cycle, data_ext);
> > > +
> > > + if (is_bus_util_event(idx))
> > > + return div64_u64(data * us_per_cycle, data_ext);
> > > +
> > > + if (is_buf_util_event(idx))
> > > + return div64_u64(data, data_ext * us_per_cycle);
> >
> > Why do we need to do all this division in the kernel? Can't we just expose
> > the underlying values and let userspace figure out what it wants to do with
> > the numbers?
> >
> Our PMU hardware support 8 sets of counters to count bandwidth, latency and
> utilization events.
>
> For example, when users set latency event, common counter will count delay
> cycles, and extern counter count number of PCIe packets automaticly. And we
> do not have a event number for counting number of PCIe packets.
>
> So this division cannot move to userspace tool.
Why can't you expose the packet counter as an extra event to userspace?
Will
