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ata: Enabling ATA Command Priorities

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This patch checks to see if an ATA device supports NCQ command priorities.
If so and the user has specified an iocontext that indicates
IO_PRIO_CLASS_RT then we build a tf with a high priority command.

This is done to improve the tail latency of commands that are high
priority by passing priority to the device.

tj: Removed trivial ata_ncq_prio_enabled() and open-coded the test.

Signed-off-by: Adam Manzanares <adam.manzanares@hgst.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Adam Manzanares
2016-10-17 11:27:29 -07:00
committed by Tejun Heo
parent 5dc8b362a2
commit 8e061784b5
5 changed files with 49 additions and 3 deletions
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35
drivers/ata/libata-core.c
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@@ -739,6 +739,7 @@ u64 ata_tf_read_block(const struct ata_taskfile *tf, struct ata_device *dev)
* @n_block: Number of blocks
* @tf_flags: RW/FUA etc...
* @tag: tag
* @class: IO priority class
*
* LOCKING:
* None.
@@ -753,7 +754,7 @@ u64 ata_tf_read_block(const struct ata_taskfile *tf, struct ata_device *dev)
*/
int ata_build_rw_tf(struct ata_taskfile *tf, struct ata_device *dev,
u64 block, u32 n_block, unsigned int tf_flags,
unsigned int tag)
unsigned int tag, int class)
{
tf->flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
tf->flags |= tf_flags;
@@ -785,6 +786,12 @@ int ata_build_rw_tf(struct ata_taskfile *tf, struct ata_device *dev,
tf->device = ATA_LBA;
if (tf->flags & ATA_TFLAG_FUA)
tf->device |= 1 << 7;
if (dev->flags & ATA_DFLAG_NCQ_PRIO) {
if (class == IOPRIO_CLASS_RT)
tf->hob_nsect |= ATA_PRIO_HIGH <<
ATA_SHIFT_PRIO;
}
} else if (dev->flags & ATA_DFLAG_LBA) {
tf->flags |= ATA_TFLAG_LBA;
@@ -2156,6 +2163,30 @@ static void ata_dev_config_ncq_non_data(struct ata_device *dev)
}
}
static void ata_dev_config_ncq_prio(struct ata_device *dev)
{
struct ata_port *ap = dev->link->ap;
unsigned int err_mask;
err_mask = ata_read_log_page(dev,
ATA_LOG_SATA_ID_DEV_DATA,
ATA_LOG_SATA_SETTINGS,
ap->sector_buf,
1);
if (err_mask) {
ata_dev_dbg(dev,
"failed to get Identify Device data, Emask 0x%x\n",
err_mask);
return;
}
if (ap->sector_buf[ATA_LOG_NCQ_PRIO_OFFSET] & BIT(3))
dev->flags |= ATA_DFLAG_NCQ_PRIO;
else
ata_dev_dbg(dev, "SATA page does not support priority\n");
}
static int ata_dev_config_ncq(struct ata_device *dev,
char *desc, size_t desc_sz)
{
@@ -2205,6 +2236,8 @@ static int ata_dev_config_ncq(struct ata_device *dev,
ata_dev_config_ncq_send_recv(dev);
if (ata_id_has_ncq_non_data(dev->id))
ata_dev_config_ncq_non_data(dev);
if (ata_id_has_ncq_prio(dev->id))
ata_dev_config_ncq_prio(dev);
}
return 0;