Re: [PATCH 1/2] dmaengine: idxd: add support for configurable max wq xfer size

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

On 8/28/2020 3:54 AM, Vinod Koul wrote:
> On 25-08-20, 13:25, Dave Jiang wrote:
>> Add sysfs attribute max_xfer_size to wq in order to allow the max xfer
>> size configured on a per wq basis. Add support code to configure
>> the valid user input on wq enable. This is a performance tuning
>> parameter.
>>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>>   drivers/dma/idxd/device.c |    2 +-
>>   drivers/dma/idxd/idxd.h   |    1 +
>>   drivers/dma/idxd/init.c   |    1 +
>>   drivers/dma/idxd/sysfs.c  |   40 ++++++++++++++++++++++++++++++++++++++++
>>   4 files changed, 43 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
>> index 14b45853aa5f..b8dbb7001933 100644
>> --- a/drivers/dma/idxd/device.c
>> +++ b/drivers/dma/idxd/device.c
>> @@ -529,7 +529,7 @@ static int idxd_wq_config_write(struct idxd_wq *wq)
>>   	wq->wqcfg.priority = wq->priority;
>>   
>>   	/* bytes 12-15 */
>> -	wq->wqcfg.max_xfer_shift = idxd->hw.gen_cap.max_xfer_shift;
>> +	wq->wqcfg.max_xfer_shift = ilog2(wq->max_xfer_bytes);
>>   	wq->wqcfg.max_batch_shift = idxd->hw.gen_cap.max_batch_shift;
>>   
>>   	dev_dbg(dev, "WQ %d CFGs\n", wq->id);
>> diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
>> index e62b4799d189..81db2a472822 100644
>> --- a/drivers/dma/idxd/idxd.h
>> +++ b/drivers/dma/idxd/idxd.h
>> @@ -114,6 +114,7 @@ struct idxd_wq {
>>   	struct sbitmap_queue sbq;
>>   	struct dma_chan dma_chan;
>>   	char name[WQ_NAME_SIZE + 1];
>> +	u64 max_xfer_bytes;
>>   };
>>   
>>   struct idxd_engine {
>> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
>> index c7c61974f20f..e5ed5750a6d0 100644
>> --- a/drivers/dma/idxd/init.c
>> +++ b/drivers/dma/idxd/init.c
>> @@ -176,6 +176,7 @@ static int idxd_setup_internals(struct idxd_device *idxd)
>>   		wq->idxd = idxd;
>>   		mutex_init(&wq->wq_lock);
>>   		wq->idxd_cdev.minor = -1;
>> +		wq->max_xfer_bytes = idxd->max_xfer_bytes;
>>   	}
>>   
>>   	for (i = 0; i < idxd->max_engines; i++) {
>> diff --git a/drivers/dma/idxd/sysfs.c b/drivers/dma/idxd/sysfs.c
>> index dcba60953217..26b3ace66782 100644
>> --- a/drivers/dma/idxd/sysfs.c
>> +++ b/drivers/dma/idxd/sysfs.c
>> @@ -1064,6 +1064,45 @@ static ssize_t wq_cdev_minor_show(struct device *dev,
>>   static struct device_attribute dev_attr_wq_cdev_minor =
>>   		__ATTR(cdev_minor, 0444, wq_cdev_minor_show, NULL);
>>   
>> +static ssize_t wq_max_transfer_size_show(struct device *dev, struct device_attribute *attr,
>> +					 char *buf)
>> +{
>> +	struct idxd_wq *wq = container_of(dev, struct idxd_wq, conf_dev);
>> +
>> +	return sprintf(buf, "%llu\n", wq->max_xfer_bytes);
>> +}
>> +
>> +static ssize_t wq_max_transfer_size_store(struct device *dev, struct device_attribute *attr,
>> +					  const char *buf, size_t count)
>> +{
>> +	struct idxd_wq *wq = container_of(dev, struct idxd_wq, conf_dev);
>> +	struct idxd_device *idxd = wq->idxd;
>> +	u64 xfer_size;
>> +	int rc;
>> +
>> +	if (wq->state != IDXD_WQ_DISABLED)
>> +		return -EPERM;
>> +
>> +	rc = kstrtou64(buf, 10, &xfer_size);
>> +	if (rc < 0)
>> +		return -EINVAL;
>> +
>> +	if (xfer_size == 0)
>> +		return -EINVAL;
>> +
>> +	xfer_size = roundup_pow_of_two(xfer_size);
>> +	if (xfer_size > idxd->max_xfer_bytes)
>> +		return -EINVAL;
>> +
>> +	wq->max_xfer_bytes = xfer_size;
>> +
>> +	return count;
>> +}
>> +
>> +static struct device_attribute dev_attr_wq_max_transfer_size =
>> +		__ATTR(max_transfer_size, 0644,
>> +		       wq_max_transfer_size_show, wq_max_transfer_size_store);
>> +
>>   static struct attribute *idxd_wq_attributes[] = {
>>   	&dev_attr_wq_clients.attr,
>>   	&dev_attr_wq_state.attr,
>> @@ -1074,6 +1113,7 @@ static struct attribute *idxd_wq_attributes[] = {
>>   	&dev_attr_wq_type.attr,
>>   	&dev_attr_wq_name.attr,
>>   	&dev_attr_wq_cdev_minor.attr,
>> +	&dev_attr_wq_max_transfer_size.attr,
> 
> ABI update for this?

Yes! Totally slipped my mind.

>