Re: [PATCH 2/3] cxl/region: Add sysfs attribute for locality attributes of CXL regions

[Dave Jiang <dave.jiang@intel.com>]

On 12/11/23 02:06, Brice Goglin wrote:
> Le 08/12/2023 à 00:31, Dave Jiang a écrit :
>> Add read/write latencies and bandwidth sysfs attributes for the enabled CXL
>> region. The bandwidth is the aggregated bandwidth of all devices that
>> contributes to the CXL region. The latency is the worst latency of the
>> device amongst all the devices that contributes to the CXL region.
> 
> 
> Hello
> 
> Which initiator do these bandwidths/latencies refer to? Local CPUs near the root port? This should be specified in the doc.

Currently I'm only storing the numbers from initiator pxm 0 to these targets in the hmat target list. I'm open to suggestions as to if a different way would be better.

> 
> Brice
> 
> 
> 
>>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>>   Documentation/ABI/testing/sysfs-bus-cxl |   40 +++++++++++++++++++++++++++++++
>>   drivers/cxl/core/region.c               |   24 +++++++++++++++++++
>>   2 files changed, 64 insertions(+)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
>> index fff2581b8033..e96f172eb6a6 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-cxl
>> +++ b/Documentation/ABI/testing/sysfs-bus-cxl
>> @@ -552,3 +552,43 @@ Description:
>>           attribute is only visible for devices supporting the
>>           capability. The retrieved errors are logged as kernel
>>           events when cxl_poison event tracing is enabled.
>> +
>> +
>> +What:        /sys/bus/cxl/devices/regionZ/read_bandwidth
>> +Date:        Apr, 2023
>> +KernelVersion:    v6.8
>> +Contact:    linux-cxl@vger.kernel.org
>> +Description:
>> +        (RO) The aggregated read bandwidth of the region. The number is
>> +        the accumulated read bandwidth of all CXL memory devices that
>> +        contributes to the region.
>> +
>> +
>> +What:        /sys/bus/cxl/devices/regionZ/write_bandwidth
>> +Date:        Apr, 2023
>> +KernelVersion:    v6.8
>> +Contact:    linux-cxl@vger.kernel.org
>> +Description:
>> +        (RO) The aggregated write bandwidth of the region. The number is
>> +        the accumulated write bandwidth of all CXL memory devices that
>> +        contributes to the region.
>> +
>> +
>> +What:        /sys/bus/cxl/devices/regionZ/read_latency
>> +Date:        Apr, 2023
>> +KernelVersion:    v6.8
>> +Contact:    linux-cxl@vger.kernel.org
>> +Description:
>> +        (RO) The read latency of the region. The number is
>> +        the worst read latency of all CXL memory devices that
>> +        contributes to the region.
>> +
>> +
>> +What:        /sys/bus/cxl/devices/regionZ/write_latency
>> +Date:        Apr, 2023
>> +KernelVersion:    v6.8
>> +Contact:    linux-cxl@vger.kernel.org
>> +Description:
>> +        (RO) The write latency of the region. The number is
>> +        the worst write latency of all CXL memory devices that
>> +        contributes to the region.
>> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
>> index d879f5702cf2..72c47f624d63 100644
>> --- a/drivers/cxl/core/region.c
>> +++ b/drivers/cxl/core/region.c
>> @@ -645,6 +645,26 @@ static ssize_t size_show(struct device *dev, struct device_attribute *attr,
>>   }
>>   static DEVICE_ATTR_RW(size);
>>   +#define ACCESS_ATTR(attrib)                    \
>> +static ssize_t attrib##_show(struct device *dev,        \
>> +               struct device_attribute *attr,    \
>> +               char *buf)                \
>> +{                                \
>> +    struct cxl_region *cxlr = to_cxl_region(dev);        \
>> +                                \
>> +    if (!cxlr->coord)                    \
>> +        return 0;                    \
>> +                                \
>> +    return sysfs_emit(buf, "%u\n",                \
>> +              cxlr->coord->attrib);            \
>> +}                                \
>> +static DEVICE_ATTR_RO(attrib)
>> +
>> +ACCESS_ATTR(read_bandwidth);
>> +ACCESS_ATTR(read_latency);
>> +ACCESS_ATTR(write_bandwidth);
>> +ACCESS_ATTR(write_latency);
>> +
>>   static struct attribute *cxl_region_attrs[] = {
>>       &dev_attr_uuid.attr,
>>       &dev_attr_commit.attr,
>> @@ -653,6 +673,10 @@ static struct attribute *cxl_region_attrs[] = {
>>       &dev_attr_resource.attr,
>>       &dev_attr_size.attr,
>>       &dev_attr_mode.attr,
>> +    &dev_attr_read_bandwidth.attr,
>> +    &dev_attr_write_bandwidth.attr,
>> +    &dev_attr_read_latency.attr,
>> +    &dev_attr_write_latency.attr,
>>       NULL,
>>   };
>>  
>>
>>