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.
Signed-off-by: Adam Manzanares <adam.manzana...@wdc.com>
---
drivers/ata/libata-core.c | 35 ++++++++++++++++++++++++++++++++++-
drivers/ata/libata-scsi.c | 6 +++++-
drivers/ata/libata.h | 2 +-
include/linux/ata.h | 6 ++++++
include/linux/libata.h | 18 ++++++++++++++++++
5 files changed, 64 insertions(+), 3 deletions(-)
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 223a770..181b530 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -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 (ata_ncq_prio_enabled(dev)) {
+ 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;
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index e207b33..18629e8 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -50,6 +50,7 @@
#include <linux/uaccess.h>
#include <linux/suspend.h>
#include <asm/unaligned.h>
+#include <linux/ioprio.h>
#include "libata.h"
#include "libata-transport.h"
@@ -1757,6 +1758,8 @@ static unsigned int ata_scsi_rw_xlat(struct
ata_queued_cmd *qc)
{
struct scsi_cmnd *scmd = qc->scsicmd;
const u8 *cdb = scmd->cmnd;
+ struct request *rq = scmd->request;
+ int class = IOPRIO_PRIO_CLASS(req_get_ioprio(rq));
unsigned int tf_flags = 0;
u64 block;
u32 n_block;
@@ -1823,7 +1826,8 @@ static unsigned int ata_scsi_rw_xlat(struct
ata_queued_cmd *qc)
qc->nbytes = n_block * scmd->device->sector_size;
rc = ata_build_rw_tf(&qc->tf, qc->dev, block, n_block, tf_flags,
- qc->tag);
+ qc->tag, class);
+
if (likely(rc == 0))
return 0;
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index 3b301a4..8f3a559 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -66,7 +66,7 @@ extern u64 ata_tf_to_lba48(const struct ata_taskfile *tf);
extern struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, int tag);
extern 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);
extern u64 ata_tf_read_block(const struct ata_taskfile *tf,
struct ata_device *dev);
extern unsigned ata_exec_internal(struct ata_device *dev,
diff --git a/include/linux/ata.h b/include/linux/ata.h
index adbc812..ebe4c3b 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -347,6 +347,7 @@ enum {
ATA_LOG_DEVSLP_DETO = 0x01,
ATA_LOG_DEVSLP_VALID = 0x07,
ATA_LOG_DEVSLP_VALID_MASK = 0x80,
+ ATA_LOG_NCQ_PRIO_OFFSET = 0x09,
/* NCQ send and receive log */
ATA_LOG_NCQ_SEND_RECV_SUBCMDS_OFFSET = 0x00,
@@ -897,6 +898,11 @@ static inline bool ata_id_has_ncq_non_data(const u16 *id)
return id[ATA_ID_SATA_CAPABILITY_2] & BIT(5);
}
+static inline bool ata_id_has_ncq_prio(const u16 *id)
+{
+ return id[ATA_ID_SATA_CAPABILITY] & BIT(12);
+}
+
static inline bool ata_id_has_trim(const u16 *id)
{
if (ata_id_major_version(id) >= 7 &&
diff --git a/include/linux/libata.h b/include/linux/libata.h
index e37d4f9..244f261 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -165,6 +165,7 @@ enum {
ATA_DFLAG_NO_UNLOAD = (1 << 17), /* device doesn't support unload */
ATA_DFLAG_UNLOCK_HPA = (1 << 18), /* unlock HPA */
ATA_DFLAG_NCQ_SEND_RECV = (1 << 19), /* device supports NCQ SEND and
RECV */
+ ATA_DFLAG_NCQ_PRIO = (1 << 20), /* device supports NCQ priority */
ATA_DFLAG_INIT_MASK = (1 << 24) - 1,
ATA_DFLAG_DETACH = (1 << 24),
@@ -341,7 +342,9 @@ enum {
ATA_SHIFT_PIO = 0,
ATA_SHIFT_MWDMA = ATA_SHIFT_PIO + ATA_NR_PIO_MODES,
ATA_SHIFT_UDMA = ATA_SHIFT_MWDMA + ATA_NR_MWDMA_MODES,
+ ATA_SHIFT_PRIO = 6,
+ ATA_PRIO_HIGH = 2,
/* size of buffer to pad xfers ending on unaligned boundaries */
ATA_DMA_PAD_SZ = 4,
@@ -1609,6 +1612,21 @@ static inline int ata_ncq_enabled(struct ata_device *dev)
ATA_DFLAG_NCQ)) == ATA_DFLAG_NCQ;
}
+/**
+ * ata_ncq_prio_enabled - Test whether NCQ prio is enabled
+ * @dev: ATA device to test for
+ *
+ * LOCKING:
+ * spin_lock_irqsave(host lock)
+ *
+ * RETURNS:
+ * 1 if NCQ prio is enabled for @dev, 0 otherwise.
+ */
+static inline int ata_ncq_prio_enabled(struct ata_device *dev)
+{
+ return (dev->flags & ATA_DFLAG_NCQ_PRIO) == ATA_DFLAG_NCQ_PRIO;
+}
+
static inline bool ata_fpdma_dsm_supported(struct ata_device *dev)
{
return (dev->flags & ATA_DFLAG_NCQ_SEND_RECV) &&
--
2.1.4
--
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