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

Dave Jiang
2020-08-28T14:32:25Z

On 8/28/2020 3:55 AM, Vinod Koul wrote:
> On 25-08-20, 13:25, Dave Jiang wrote:
>> Add sysfs attribute max_batch_size to wq in order to allow the max batch
>> 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 | 38 ++++++++++++++++++++++++++++++++++++++
>> 4 files changed, 41 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
>> index b8dbb7001933..00dab1465ca3 100644
>> --- a/drivers/dma/idxd/device.c
>> +++ b/drivers/dma/idxd/device.c
>> @@ -530,7 +530,7 @@ static int idxd_wq_config_write(struct idxd_wq *wq)
>>
>> /* bytes 12-15 */
>> wq->wqcfg.max_xfer_shift = ilog2(wq->max_xfer_bytes);
>> - wq->wqcfg.max_batch_shift = idxd->hw.gen_cap.max_batch_shift;
>> + wq->wqcfg.max_batch_shift = ilog2(wq->max_batch_size);
>>
>> dev_dbg(dev, "WQ %d CFGs\n", wq->id);
>> for (i = 0; i < 8; i++) {
>> diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
>> index 81db2a472822..e8bec6eb9f7e 100644
>> --- a/drivers/dma/idxd/idxd.h
>> +++ b/drivers/dma/idxd/idxd.h
>> @@ -115,6 +115,7 @@ struct idxd_wq {
>> struct dma_chan dma_chan;
>> char name[WQ_NAME_SIZE + 1];
>> u64 max_xfer_bytes;
>> + u32 max_batch_size;
>> };
>>
>> struct idxd_engine {
>> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
>> index e5ed5750a6d0..11e5ce168177 100644
>> --- a/drivers/dma/idxd/init.c
>> +++ b/drivers/dma/idxd/init.c
>> @@ -177,6 +177,7 @@ static int idxd_setup_internals(struct idxd_device *idxd)
>> mutex_init(&wq->wq_lock);
>> wq->idxd_cdev.minor = -1;
>> wq->max_xfer_bytes = idxd->max_xfer_bytes;
>> + wq->max_batch_size = idxd->max_batch_size;
>> }
>>
>> for (i = 0; i < idxd->max_engines; i++) {
>> diff --git a/drivers/dma/idxd/sysfs.c b/drivers/dma/idxd/sysfs.c
>> index 26b3ace66782..c5f19802cb9e 100644
>> --- a/drivers/dma/idxd/sysfs.c
>> +++ b/drivers/dma/idxd/sysfs.c
>> @@ -1103,6 +1103,43 @@ 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 ssize_t wq_max_batch_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, "%u\n", wq->max_batch_size);
>> +}
>> +
>> +static ssize_t wq_max_batch_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;
>> + u32 batch_size;
>> + int rc;
>> +
>> + if (wq->state != IDXD_WQ_DISABLED)
>> + return -EPERM;
>> +
>> + rc = kstrtou32(buf, 10, &batch_size);
>> + if (rc < 0)
>> + return -EINVAL;
>> +
>> + if (batch_size == 0)
>> + return -EINVAL;
>
> seems quite similar to previous patch, maybe a helper to get the value?

Ok I'll look into that.

>
>> +
>> + batch_size = roundup_pow_of_two(batch_size);
>> + if (batch_size > idxd->max_batch_size)
>> + return -EINVAL;
>> +
>> + wq->max_batch_size = batch_size;
>> +
>> + return count;
>> +}
>> +
>> +static struct device_attribute dev_attr_wq_max_batch_size =
>> + __ATTR(max_batch_size, 0644, wq_max_batch_size_show, wq_max_batch_size_store);
>> +
>> static struct attribute *idxd_wq_attributes[] = {
>> &dev_attr_wq_clients.attr,
>> &dev_attr_wq_state.attr,
>> @@ -1114,6 +1151,7 @@ static struct attribute *idxd_wq_attributes[] = {
>> &dev_attr_wq_name.attr,
>> &dev_attr_wq_cdev_minor.attr,
>> &dev_attr_wq_max_transfer_size.attr,
>> + &dev_attr_wq_max_batch_size.attr,
>
> ABI?

Yes will add.

>
>> NULL,
>> };
>>
>