Re: [PATCH v2] perf/hx_arm_ni: Support uncore ARM NI-700 PMU

[Yang Jialong 杨佳龙]

在 2024/1/31 18:36, Krzysztof Kozlowski 写道:
> On 31/01/2024 11:07, Yang Jialong 杨佳龙 wrote:
> > 在 2024/1/31 17:38, Krzysztof Kozlowski 写道:
> > > On 31/01/2024 10:07, Yang Jialong 杨佳龙 wrote:
> > > > 在 2024/1/31 15:59, Krzysztof Kozlowski 写道:
> > > > > On 31/01/2024 08:08, JiaLong.Yang wrote:
> > > > > > This code is based on uncore PMUs arm_smmuv3_pmu and arm-cmn.
> > > > > > One ni-700 can have many clock domains. Each of them has only one PMU.
> > > > > > Here one PMU corresponds to one 'struct ni_pmu' instance.
> > > > > > PMU name will be ni_pmu_N_M, which N means different NI-700s and M means
> > > > > > different PMU in one NI-700. If only one NI-700 found in NI-700, name will
> > > > > > be ni_pmu_N.
> > > > > > Node interface event name will be xxni_N_eventname, such as
> > > > > > asni_0_rdreq_any. There are many kinds of type of nodes in one clock
> > > > > > domain. Also means that there are many kinds of that in one PMU. So we
> > > > > > distinguish them by xxni string. Besides, maybe there are many nodes
> > > > > > have same type. So we have number N in event name.
> > > > > > By ni_pmu_0_0/asni_0_rdreq_any/, we can pinpoint accurate bus traffic.
> > > > > > Example1: perf stat -a -e ni_pmu_0_0/asni_0_rdreq_any/,ni_pmu_0_0/cycles/
> > > > > > EXample2: perf stat -a -e ni_pmu_0_0/asni,id=0,event=0x0/
> > > > > >
> > > > > > Signed-off-by: JiaLong.Yang <jialong.yang@xxxxxxxxxxxx>
> > > > > > ---
> > > > > > v1 --> v2:
> > > > > > 1. Submit MAINTANER Documentation/ files seperately.
> > > > >
> > > > > SEPARATE PATCHES, not patchsets. You have now checkpatch warnings
> > > > > because of this...
> > > >
> > > > ...OK. But the MAINTANER file changing should be given in which one
> > > > patches.
> > > > I will submit patch v3 after talking and your permission.
> > > >
> > > > > > 2. Delete some useless info printing.
> > > > > > 3. Change print from pr_xxx to dev_xxx.
> > > > > > 4. Fix more than 75 length log info.
> > > > > > 5. Fix dts attribute pccs-id.
> > > > > > 6. Fix generic name according to DT specification.
> > > > > > 7. Some indentation.
> > > > > > 8. Del of_match_ptr macro.
> > > > > >
> > > > > >     drivers/perf/Kconfig     |   11 +
> > > > > >     drivers/perf/Makefile    |    1 +
> > > > > >     drivers/perf/hx_arm_ni.c | 1284 ++++++++++++++++++++++++++++++++++++++
> > > > > >     3 files changed, 1296 insertions(+)
> > > > > >     create mode 100644 drivers/perf/hx_arm_ni.c
> > > > > >
> > > > > > diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> > > > > > index ec6e0d9194a1..95ef8b13730f 100644
> > > > > > --- a/drivers/perf/Kconfig
> > > > > > +++ b/drivers/perf/Kconfig
> > > > > > @@ -241,4 +241,15 @@ config CXL_PMU
> > > > > >     
> > > > > >     	  If unsure say 'm'.
> > > > > >     
> > > > > > +config HX_ARM_NI_PMU
> > > > > > +       tristate "HX ARM NI-700 PMU"
> > > > > > +       depends on PPC_HX_C2000 && 64BIT
> > > > >
> > > > > 1. There is no PPC_HX_C2000.
> > > >
> > > > I have been used to using this macro. However this macro is not existed
> > > > in mainline.
> > > > I will replace it with ARM64. And del involved C code if OK.
> > > >
> > > > 64bit:
> > > > __ffs(unsigned long) and __fls(unsigned long) will be wrong in 32bit. I
> > > > pass a u64 argument.
> > >
> > > One thing is where the code is supposed to run, second thing is compile
> > > testing.
> >
> > Now run on my company product, a 64bit PowerPC...
> > But I think it's general for 64bit systems.
> >
> > > Why do you use __ffs, not __ffs64 which takes u64 if you really want
> > > only 64bit argument? unsigned long != u64, so your code is not
> > > architecture independent. You claim you wrote it on purpose as
> > > non-architecture-independent, but then I claim it's a bug. We are
> > > supposed to write code which is portable, as much as possible, assuming
> > > it does not affect readability.
> >
> > I write code in v5.18, there are __ffs64() and fls64(). Asymmetric.
>
> Sorry, that's a no go.
>
> That's some very, very old kernel. Do not develop on old kernels, but on
> mainline. I also suspect that by basing your work on old kernel, you
> duplicate a lot of issues already fixed.
>
> > There are some difference in return val between __ffs() and ffs64().
> > __ffs(0) and ffs64(0) will give different value.
>
> __ffs64 calls __ffs, so why would results be different?
>
> Anyway, that's not really excuse.

OK. Follow mainline.

> > And I'm sure code run in 64bit. So I choose to use __ffs and __fls.
> >
> > Maybe it could be compatbile with 32bit. But I don't have a environment
> > to test this.
> > > > struct ni_hw_perf_event will be big than limit.
> > > > BUILD_BUG_ON(sizeof(struct ni_hw_perf_event) > offsetof(struct
> > > > hw_perf_event, target));
> > >
> > > And why do you need to use any of such code? Please open one of hundreds
> > > of other drivers which work correctly on 32 and 64-bit platforms.
> >
> > Code for 64bit.
> > This code is to avoid struct ni_hw_perf_event is too big than struct
> > hw_perf_event::target.
>
> 1. Why would that matter? target is task_struct. It's size does not
> matter. Maybe its offset matters, but not size.

Offset.

> 2. So you claim that on 32-bit system the structure will be bigger than
> on 64-bit system?

The structure will exceed the offset in 32bit. Maybe because the latter 
changed more.
OK. Dont care please.

> > I learn it from arm-cmn.c.
>
> Are you copying patterns because they are good patterns or just because
> you decided to copy?

Maybe this way is not very good for event framework.
OK. Not an official way.

> > ni_hw_perf_event will replace hw_perf_event.
> > I will put some useful information in it with less space and good field
> > names.
> > But I can't exceed a limit.
> >
> > > > > 2. Nothing justified dependency on 64bit. Drop or explain. Your previous
> > > > > message did not provide real rationale.
> > > >
> > > > If ARM64, then drop.
> > >
> > > ...
> > >
> > > ...
> > >
> > > > > > +	/* Step2: Traverse all clock domains. */
> > > > > > +	for (cd_idx = 0; cd_idx < ni->cd_num; cd_idx++) {
> > > > > > +		cd = cd_arrays[cd_idx];
> > > > > > +
> > > > > > +		num = ni_child_number(cd);
> > > > > > +		dev_dbg(dev, "The %dth clock domain has %d child nodes:", cd_idx, num);
> > > > > > +
> > > > > > +		/* Omit pmu node */
> > > > > > +		ni_pmu = devm_kzalloc(dev, struct_size(ni_pmu, ev_src_nodes, num - 1),
> > > > > > +				      GFP_KERNEL);
> > > > > > +		ni_pmu->ev_src_num = num - 1;
> > > > > > +
> > > > > > +		if (!ni_pmu)
> > > > > > +			return -ENOMEM;
> > > > > > +
> > > > > > +		num_idx = 0;
> > > > > > +		for (nd_idx = 0; nd_idx < num; nd_idx++) {
> > > > > > +			nd = ni_child_pointer(pbase, cd, nd_idx);
> > > > > > +
> > > > > > +			node.base = nd;
> > > > > > +			node.node_type = ni_node_node_type(nd);
> > > > > > +
> > > > > > +			if (unlikely(ni_node_type(nd) == NI_PMU))
> > > > > > +				ni_pmu->pmu_node = node;
> > > > > > +			else
> > > > > > +				ni_pmu->ev_src_nodes[num_idx++] = node;
> > > > > > +			dev_dbg(dev, "  name: %s   id: %d", ni_node_name[node.type], node.id);
> > > > > > +		}
> > > > > > +
> > > > > > +		ni_pmu->dev = dev;
> > > > > > +		ni_pmu->ni = ni;
> > > > > > +		ni->ni_pmus[cd_idx] = ni_pmu;
> > > > > > +	}
> > > > > > +
> > > > > > +	devm_kfree(dev, cd_arrays);
> > > > >
> > > > > Why? If it is not device-lifetime then allocate with usual way.
> > > >
> > > > No device-lifetime.
> > > > Will allocate in stack.
> > >
> > > I was thinking about kzalloc. But if array is small, stack could be as well.
> >
> > If I have to return before devm_kfree because of wrong, I will have to use:
> >
> > goto out;
> >
> > out:
> > kfree();
> >
> > But if I use devm_kzalloc, I will not be worried about that. Even if no
>
> devm* is not for that purpose. devm is for device-managed allocations.
> Device does not manage your allocation.
>
> > device-lifetime.
> > Isn't this a good way?
>
> Then you want cleanup.h and use proper __free().

Good NEW API. It does what I want.
Learned more. Thanks.

> Best regards,
> Krzysztof