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Message-ID:
<DU2PR04MB882224AF65845B2AB0F30B998C7D2@DU2PR04MB8822.eurprd04.prod.outlook.com>
Date: Tue, 30 Jan 2024 02:52:32 +0000
From: Xu Yang <xu.yang_2@....com>
To: Frank Li <frank.li@....com>, "will@...nel.org" <will@...nel.org>,
"mark.rutland@....com" <mark.rutland@....com>, "robh+dt@...nel.org"
<robh+dt@...nel.org>, "krzysztof.kozlowski+dt@...aro.org"
<krzysztof.kozlowski+dt@...aro.org>, "conor+dt@...nel.org"
<conor+dt@...nel.org>, "shawnguo@...nel.org" <shawnguo@...nel.org>,
"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>, "kernel@...gutronix.de"
<kernel@...gutronix.de>, "festevam@...il.com" <festevam@...il.com>,
"john.g.garry@...cle.com" <john.g.garry@...cle.com>, "jolsa@...nel.org"
<jolsa@...nel.org>, "namhyung@...nel.org" <namhyung@...nel.org>,
"irogers@...gle.com" <irogers@...gle.com>
CC: dl-linux-imx <linux-imx@....com>, "mike.leach@...aro.org"
<mike.leach@...aro.org>, "leo.yan@...aro.org" <leo.yan@...aro.org>,
"peterz@...radead.org" <peterz@...radead.org>, "mingo@...hat.com"
<mingo@...hat.com>, "acme@...nel.org" <acme@...nel.org>,
"alexander.shishkin@...ux.intel.com" <alexander.shishkin@...ux.intel.com>,
"adrian.hunter@...el.com" <adrian.hunter@...el.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>, "devicetree@...r.kernel.org"
<devicetree@...r.kernel.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>, "linux-perf-users@...r.kernel.org"
<linux-perf-users@...r.kernel.org>
Subject: RE: [PATCH v3 3/4] perf: imx_perf: limit counter ID from user space
and optimize counter usage
Hi Frank,
> > Subject: [PATCH v3 3/4] perf: imx_perf: limit counter ID from user space and
> > optimize counter usage
> >
> > The user can pass any counter ID to perf app. However, current pmu driver
> > doesn't judge the validity of the counter ID. This will add necessary
> > check for counter ID from user space. Besides, this pmu has 10 counters
> > except cycle counter which can be used to count reference events and
> > counter specific evnets. This will also add supports to auto allocate
> > counter if the user doesn't pass it the perf. Then, the usage of counter
> > will be optimized.
> >
> > Signed-off-by: Xu Yang <xu.yang_2@....com>
> >
> > ---
> > Changes in v2:
> > - limit counter ID from user to 0-10
> > - combine dynamic and static allocation of counter
> > Changes in v3:
> > - no changes
> > ---
> > drivers/perf/fsl_imx9_ddr_perf.c | 69
> > +++++++++++++++++++++++++++++++-
> > 1 file changed, 67 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/perf/fsl_imx9_ddr_perf.c
> > b/drivers/perf/fsl_imx9_ddr_perf.c
> > index fd118773508d..4bb80050920c 100644
> > --- a/drivers/perf/fsl_imx9_ddr_perf.c
> > +++ b/drivers/perf/fsl_imx9_ddr_perf.c
> > @@ -51,6 +51,7 @@
> >
> > #define NUM_COUNTERS 11
> > #define CYCLES_COUNTER 0
> > +#define CYCLES_EVENT_ID 0
> >
> > #define to_ddr_pmu(p) container_of(p, struct ddr_pmu, pmu)
> >
> > @@ -235,6 +236,14 @@ static struct attribute *ddr_perf_events_attrs[] = {
> > NULL,
> > };
> >
> > +static bool ddr_perf_is_specific_event(int event)
>
> Why call specific? Name is too general. Such as is_fixed? Or Is_with_filter?
> Need know what specific?
There are only two types of event: reference event and counter specific evnet.
To make it clear, I'll change it to ddr_perf_is_counter_specific_event().
>
> > +{
> > + if (event >= 64 && event <= 73)
> > + return true;
> > + else
> > + return false;
> > +}
> > +
> > static const struct attribute_group ddr_perf_events_attr_group = {
> > .name = "events",
> > .attrs = ddr_perf_events_attrs,
> > @@ -507,6 +516,7 @@ static int ddr_perf_event_init(struct perf_event
> > *event)
> > struct ddr_pmu *pmu = to_ddr_pmu(event->pmu);
> > struct hw_perf_event *hwc = &event->hw;
> > struct perf_event *sibling;
> > + int event_id, counter;
> >
> > if (event->attr.type != event->pmu->type)
> > return -ENOENT;
> > @@ -519,6 +529,18 @@ static int ddr_perf_event_init(struct perf_event
> > *event)
> > return -EOPNOTSUPP;
> > }
> >
> > + counter = (event->attr.config & 0xFF00) >> 8;
>
> Define 0xFF00?
Okay.
>
> > + if (counter > NUM_COUNTERS) {
> > + dev_warn(pmu->dev, "Only counter 0-10 is supported!\n");
> > + return -EINVAL;
> > + }
> > +
> > + event_id = event->attr.config & 0x00FF;
>
> same for hardcode 0x00FF
Okay.
Thanks,
Xu Yang
>
> > + if (ddr_perf_is_specific_event(event_id) && counter == 0) {
> > + dev_err(pmu->dev, "Need specify counter for counter
> > specific events!\n");
> > + return -EINVAL;
> > + }
> > +
> > /*
> > * We must NOT create groups containing mixed PMUs, although
> > software
> > * events are acceptable (for example to create a CCN group
> > @@ -552,6 +574,39 @@ static void ddr_perf_event_start(struct perf_event
> > *event, int flags)
> > hwc->state = 0;
> > }
> >
> > +static int ddr_perf_alloc_counter(struct ddr_pmu *pmu, int event, int
> > counter)
> > +{
> > + int i;
> > +
> > + if (event == CYCLES_EVENT_ID) {
> > + /*
> > + * Always map cycle event to counter 0.
> > + * Cycles counter is dedicated for cycle event
> > + * can't used for the other events.
> > + */
> > + if (pmu->events[CYCLES_COUNTER] == NULL)
> > + return CYCLES_COUNTER;
> > + } else if (counter != 0) {
> > + /*
> > + * 1. ddr_perf_event_init() will make sure counter
> > + * is not 0 for counter specific events.
> > + * 2. Allow specify counter for referene event too.
> > + */
> > + if (pmu->events[counter] == NULL)
> > + return counter;
> > + } else {
> > + /*
> > + * Counter may be 0 if user doesn't specify it.
> > + * Auto allocate counter for referene event.
> > + */
> > + for (i = 1; i < NUM_COUNTERS; i++)
> > + if (pmu->events[i] == NULL)
> > + return i;
> > + }
> > +
> > + return -ENOENT;
> > +}
> > +
> > static int ddr_perf_event_add(struct perf_event *event, int flags)
> > {
> > struct ddr_pmu *pmu = to_ddr_pmu(event->pmu);
> > @@ -559,9 +614,17 @@ static int ddr_perf_event_add(struct perf_event
> > *event, int flags)
> > int cfg = event->attr.config;
> > int cfg1 = event->attr.config1;
> > int cfg2 = event->attr.config2;
> > - int counter;
> > + int event_id, counter;
> >
> > - counter = (cfg & 0x0000FF00) >> 8;
> > + event_id = cfg & 0x00FF;
> > + counter = (cfg & 0xFF00) >> 8;
> > +
> > + /* check if counter is available */
> > + counter = ddr_perf_alloc_counter(pmu, event_id, counter);
> > + if (counter < 0) {
> > + dev_dbg(pmu->dev, "There are not enough counters\n");
> > + return -EOPNOTSUPP;
> > + }
> >
> > pmu->events[counter] = event;
> > pmu->active_events++;
> > @@ -597,9 +660,11 @@ static void ddr_perf_event_del(struct perf_event
> > *event, int flags)
> > {
> > struct ddr_pmu *pmu = to_ddr_pmu(event->pmu);
> > struct hw_perf_event *hwc = &event->hw;
> > + int counter = hwc->idx;
> >
> > ddr_perf_event_stop(event, PERF_EF_UPDATE);
> >
> > + pmu->events[counter] = NULL;
> > pmu->active_events--;
> > hwc->idx = -1;
> > }
> > --
> > 2.34.1
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