Re: [PATCH net-next v2] net: phy: Maintain MDIO device and bus statistics

Florian Fainelli
2020-01-16T00:01:46Z

Hi Andrew,

On 1/15/20 3:53 PM, Andrew Lunn wrote:
>> +#define MDIO_BUS_STATS_ADDR_ATTR(field, addr, file) \
>> +static ssize_t mdio_bus_##field##_##addr##_show(struct device *dev, \
>> + struct device_attribute *attr, \
>> + char *buf) \
>> +{ \
>> + struct mii_bus *bus = to_mii_bus(dev); \
>> + return mdio_bus_stats_##field##_show(&bus->stats[addr], buf); \
>> +} \
>
> Hi Florian
>
> Lots of Macro magic here. But it is reasonably understandable.
> However, the compiler is maybe not doing the best of jobs:
>
> 00000064 l F .text 00000030 mdio_bus_reads_31_show
> 00000094 l F .text 00000030 mdio_bus_reads_30_show
> 000000c4 l F .text 00000030 mdio_bus_reads_29_show
> 000000f4 l F .text 00000030 mdio_bus_reads_28_show
> 00000124 l F .text 00000030 mdio_bus_reads_27_show
> 00000154 l F .text 00000030 mdio_bus_reads_26_show
> 00000184 l F .text 00000030 mdio_bus_reads_25_show
> 000001b4 l F .text 00000034 mdio_bus_reads_24_show
> 000001e8 l F .text 00000034 mdio_bus_reads_23_show
> 0000021c l F .text 00000034 mdio_bus_reads_22_show
> 00000250 l F .text 00000034 mdio_bus_reads_21_show
> 00000284 l F .text 00000034 mdio_bus_reads_20_show
> 000002b8 l F .text 00000034 mdio_bus_reads_19_show
> 000002ec l F .text 00000034 mdio_bus_reads_18_show
> 00000320 l F .text 00000034 mdio_bus_reads_17_show
> 00000354 l F .text 00000034 mdio_bus_reads_16_show
> 00000388 l F .text 00000034 mdio_bus_reads_15_show
> 000003bc l F .text 00000034 mdio_bus_reads_14_show
> 000003f0 l F .text 00000034 mdio_bus_reads_13_show
> 00000424 l F .text 00000034 mdio_bus_reads_12_show
> 00000458 l F .text 00000034 mdio_bus_reads_11_show
> 0000048c l F .text 00000034 mdio_bus_reads_10_show
> 000004c0 l F .text 00000034 mdio_bus_reads_9_show
> 000004f4 l F .text 00000034 mdio_bus_reads_8_show
> 00000528 l F .text 00000034 mdio_bus_reads_7_show
> 0000055c l F .text 00000034 mdio_bus_reads_6_show
> 00000590 l F .text 00000034 mdio_bus_reads_5_show
> 000005c4 l F .text 00000034 mdio_bus_reads_4_show
> 000005f8 l F .text 00000034 mdio_bus_reads_3_show
> 0000062c l F .text 00000034 mdio_bus_reads_2_show
> 00000660 l F .text 00000034 mdio_bus_reads_1_show
> 00000694 l F .text 00000034 mdio_bus_reads_0_show
>
> It appears to be inlining everything, so end up with lots of
> functions, and they are not tiny.
>
> I'm wondering if we can get ride of this per address
> reads/write/transfer function. Could you stuff the addr into var of
> struct dev_ext_attribute?

That is a great suggestion, thanks! This should reduce the number of
those _show functions, expect v3 soon.
--
Florian