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Message-ID: <20221109170954.000036e2@Huawei.com>
Date: Wed, 9 Nov 2022 17:09:54 +0000
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Yicong Yang <yangyicong@...wei.com>
CC: Shaokun Zhang <zhangshaokun@...ilicon.com>, <liuqi6124@...il.com>,
Jonathan Corbet <corbet@....net>,
Will Deacon <will@...nel.org>,
"Mark Rutland" <mark.rutland@....com>,
John Garry <john.garry@...wei.com>,
<linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-doc@...r.kernel.org>, <linuxarm@...wei.com>,
<f.fangjian@...wei.com>, <prime.zeng@...wei.com>
Subject: Re: [PATCH 3/3] drivers/perf: hisi: Add TLP filter support
On Tue, 25 Oct 2022 19:32:42 +0800
Yicong Yang <yangyicong@...wei.com> wrote:
> From: Yicong Yang <yangyicong@...ilicon.com>
>
> The PMU support to filter the TLP when counting the bandwidth with below
> options:
>
> - only count the TLP headers
> - only count the TLP payloads
> - count both TLP headers and payloads
>
> In the current driver it's default to count the TLP payloads only, which
> will have an implicity side effects that on the traffic only have header
> only TLPs, we'll get no data.
>
> Make this user configuration through "len_mode" parameter and make it
> default to count both TLP headers and payloads when user not specified.
> Also update the documentation for it.
I suppose this filter option is useful. Default of "both" makes sense.
A few minor suggestions inline.
Jonathan
>
> Signed-off-by: Yicong Yang <yangyicong@...ilicon.com>
> ---
> .../admin-guide/perf/hisi-pcie-pmu.rst | 20 +++++++++++++++++++
> drivers/perf/hisilicon/hisi_pcie_pmu.c | 14 ++++++++++++-
> 2 files changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/admin-guide/perf/hisi-pcie-pmu.rst b/Documentation/admin-guide/perf/hisi-pcie-pmu.rst
> index bbe66480ff85..83a2ef11b1a0 100644
> --- a/Documentation/admin-guide/perf/hisi-pcie-pmu.rst
> +++ b/Documentation/admin-guide/perf/hisi-pcie-pmu.rst
> @@ -104,3 +104,23 @@ when TLP length < threshold.
> Example usage of perf::
>
> $# perf stat -e hisi_pcie0_core0/rx_mrd_flux,thr_len=0x4,thr_mode=1/ sleep 5
> +
> +4. TLP Length filter
> +When counting bandwidth, the data can be composed of certain parts of TLP
> +packets. You can specify it through "len_mode":
> +
> +- 2'b00: Reserved (Do not use this since the behaviour is undefined)
> +- 2'b01: Bandwidth of TLP payloads
> +- 2'b10: Bandwidth of TLP headers
> +- 2'b11: Bandwidth of both TLP payloads and headers
We could describe this as a bitmap, but i think you are right in thinking
it is clearer to present it as 3 values as not always obvious that the bitmap
is controlling sum of two different things.
> +
> +For example, "len_mode=2" means only counting the bandwidth of TLP headers
> +and "len_mode=3" means the final bandwidth data is composed of both TLP
> +headers and payloads. You need to carefully using this to avoid losing
> +data.
I'm not sure this warning makes sense. If user has set this filter then
they don't want to measure the types they haven't picked. I would drop
the warning and example. It is fairly obvious that no_counts == nothing
to count.
> For example you're likely to get no counts by "len_mode=1" if the TLPs
> +on the traffic has no payload.
Drop this example.
> This config is optional, by default it'll
> +be 2'b11.
Anything with a default is inherently optional, so could we just say
Default value if not specified is 2'b11.
> +
> +Example usage of perf::
> +
> + $# perf stat -e hisi_pcie0_core0/rx_mrd_flux,len_mode=0x1/ sleep 5
> diff --git a/drivers/perf/hisilicon/hisi_pcie_pmu.c b/drivers/perf/hisilicon/hisi_pcie_pmu.c
> index 071e63d9a9ac..6fee0b6e163b 100644
> --- a/drivers/perf/hisilicon/hisi_pcie_pmu.c
> +++ b/drivers/perf/hisilicon/hisi_pcie_pmu.c
> @@ -47,10 +47,14 @@
> #define HISI_PCIE_EVENT_M GENMASK_ULL(15, 0)
> #define HISI_PCIE_THR_MODE_M GENMASK_ULL(27, 27)
> #define HISI_PCIE_THR_M GENMASK_ULL(31, 28)
> +#define HISI_PCIE_LEN_M GENMASK_ULL(35, 34)
> #define HISI_PCIE_TARGET_M GENMASK_ULL(52, 36)
> #define HISI_PCIE_TRIG_MODE_M GENMASK_ULL(53, 53)
> #define HISI_PCIE_TRIG_M GENMASK_ULL(59, 56)
>
> +/* Default config of TLP length mode, will count both TLP headers and payloads */
> +#define HISI_PCIE_LEN_M_DEFAULT 3ULL
> +
> #define HISI_PCIE_MAX_COUNTERS 8
> #define HISI_PCIE_REG_STEP 8
> #define HISI_PCIE_THR_MAX_VAL 10
> @@ -91,6 +95,7 @@ HISI_PCIE_PMU_FILTER_ATTR(thr_len, config1, 3, 0);
> HISI_PCIE_PMU_FILTER_ATTR(thr_mode, config1, 4, 4);
> HISI_PCIE_PMU_FILTER_ATTR(trig_len, config1, 8, 5);
> HISI_PCIE_PMU_FILTER_ATTR(trig_mode, config1, 9, 9);
> +HISI_PCIE_PMU_FILTER_ATTR(len_mode, config1, 11, 10);
> HISI_PCIE_PMU_FILTER_ATTR(port, config2, 15, 0);
> HISI_PCIE_PMU_FILTER_ATTR(bdf, config2, 31, 16);
>
> @@ -215,8 +220,8 @@ static void hisi_pcie_pmu_config_filter(struct perf_event *event)
> {
> struct hisi_pcie_pmu *pcie_pmu = to_pcie_pmu(event->pmu);
> struct hw_perf_event *hwc = &event->hw;
> + u64 port, trig_len, thr_len, len_mode;
> u64 reg = HISI_PCIE_INIT_SET;
> - u64 port, trig_len, thr_len;
>
> /* Config HISI_PCIE_EVENT_CTRL according to event. */
> reg |= FIELD_PREP(HISI_PCIE_EVENT_M, hisi_pcie_get_real_event(event));
> @@ -245,6 +250,12 @@ static void hisi_pcie_pmu_config_filter(struct perf_event *event)
> reg |= HISI_PCIE_THR_EN;
> }
>
> + len_mode = hisi_pcie_get_len_mode(event);
> + if (len_mode)
> + reg |= FIELD_PREP(HISI_PCIE_LEN_M, len_mode);
> + else
> + reg |= FIELD_PREP(HISI_PCIE_LEN_M, HISI_PCIE_LEN_M_DEFAULT);
> +
> hisi_pcie_pmu_writeq(pcie_pmu, HISI_PCIE_EVENT_CTRL, hwc->idx, reg);
> }
>
> @@ -711,6 +722,7 @@ static struct attribute *hisi_pcie_pmu_format_attr[] = {
> HISI_PCIE_PMU_FORMAT_ATTR(thr_mode, "config1:4"),
> HISI_PCIE_PMU_FORMAT_ATTR(trig_len, "config1:5-8"),
> HISI_PCIE_PMU_FORMAT_ATTR(trig_mode, "config1:9"),
> + HISI_PCIE_PMU_FORMAT_ATTR(len_mode, "config1:10-11"),
> HISI_PCIE_PMU_FORMAT_ATTR(port, "config2:0-15"),
> HISI_PCIE_PMU_FORMAT_ATTR(bdf, "config2:16-31"),
> NULL
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