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dmaengine: idxd: add support for configurable max wq batch size
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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>
Link: https://lore.kernel.org/r/159865273617.29141.4383066301730821749.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
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Dave Jiang authored and Vinod Koul committed Sep 3, 2020
1 parent d7aad55 commit e7184b1
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Showing 5 changed files with 61 additions and 7 deletions.
7 changes: 7 additions & 0 deletions Documentation/ABI/stable/sysfs-driver-dma-idxd
Original file line number Diff line number Diff line change
Expand Up @@ -177,6 +177,13 @@ Contact: dmaengine@vger.kernel.org
Description: The max transfer sized for this workqueue. Cannot exceed device
max transfer size. Configurable parameter.

What: /sys/bus/dsa/devices/wq<m>.<n>/max_batch_size
Date: Aug 28, 2020
KernelVersion: 5.10.0
Contact: dmaengine@vger.kernel.org
Description: The max batch size for this workqueue. Cannot exceed device
max batch size. Configurable parameter.

What: /sys/bus/dsa/devices/engine<m>.<n>/group_id
Date: Oct 25, 2019
KernelVersion: 5.6.0
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2 changes: 1 addition & 1 deletion drivers/dma/idxd/device.c
Original file line number Diff line number Diff line change
Expand Up @@ -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++) {
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1 change: 1 addition & 0 deletions drivers/dma/idxd/idxd.h
Original file line number Diff line number Diff line change
Expand Up @@ -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 {
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1 change: 1 addition & 0 deletions drivers/dma/idxd/init.c
Original file line number Diff line number Diff line change
Expand Up @@ -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++) {
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57 changes: 51 additions & 6 deletions drivers/dma/idxd/sysfs.c
Original file line number Diff line number Diff line change
Expand Up @@ -1064,6 +1064,21 @@ 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 int __get_sysfs_u64(const char *buf, u64 *val)
{
int rc;

rc = kstrtou64(buf, 0, val);
if (rc < 0)
return -EINVAL;

if (*val == 0)
return -EINVAL;

*val = roundup_pow_of_two(*val);
return 0;
}

static ssize_t wq_max_transfer_size_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
Expand All @@ -1083,14 +1098,10 @@ static ssize_t wq_max_transfer_size_store(struct device *dev, struct device_attr
if (wq->state != IDXD_WQ_DISABLED)
return -EPERM;

rc = kstrtou64(buf, 0, &xfer_size);
rc = __get_sysfs_u64(buf, &xfer_size);
if (rc < 0)
return -EINVAL;

if (xfer_size == 0)
return -EINVAL;
return rc;

xfer_size = roundup_pow_of_two(xfer_size);
if (xfer_size > idxd->max_xfer_bytes)
return -EINVAL;

Expand All @@ -1103,6 +1114,39 @@ 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;
u64 batch_size;
int rc;

if (wq->state != IDXD_WQ_DISABLED)
return -EPERM;

rc = __get_sysfs_u64(buf, &batch_size);
if (rc < 0)
return rc;

if (batch_size > idxd->max_batch_size)
return -EINVAL;

wq->max_batch_size = (u32)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,
Expand All @@ -1114,6 +1158,7 @@ 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,
};

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