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Commit 8e061784 authored by Adam Manzanares's avatar Adam Manzanares Committed by Tejun Heo
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ata: Enabling ATA Command Priorities 



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: default avatarAdam Manzanares <adam.manzanares@hgst.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 5dc8b362

drivers/ata/libata-core.c

+34 −1
Original line number Diff line number Diff line
@@ -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;

drivers/ata/libata-scsi.c

+5 −1
Original line number Diff line number Diff line
@@ -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"
@@ -1755,6 +1756,8 @@ 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;
@@ -1821,7 +1824,8 @@ 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;

drivers/ata/libata.h

+1 −1
Original line number Diff line number Diff line
@@ -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,

include/linux/ata.h

+6 −0
Original line number Diff line number Diff line
@@ -348,6 +348,7 @@ 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,
@@ -940,6 +941,11 @@ 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 &&

include/linux/libata.h

+3 −0
Original line number Diff line number Diff line
@@ -166,6 +166,7 @@ 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),
@@ -342,7 +343,9 @@ 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,