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

Dave Jiang
2020-08-25T20:25:09Z

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;
+
+ 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,
NULL,
};