Commit 415ccd98 authored by Mike Christie's avatar Mike Christie Committed by Martin K. Petersen
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scsi: target: iblock: Add backend plug/unplug callouts 

This patch adds plug/unplug callouts for iblock. For an initiator driver
like iSCSI which wants to pass multiple cmds to its xmit thread instead of
one cmd at a time, this increases IOPS by around 10% with vhost-scsi
(combined with the last patches we can see a total 40-50% increase). For
driver combos like tcm_loop and faster drivers like the iSER initiator, we
can still see IOPS increase by 20-30% when tcm_loop's nr_hw_queues setting
is also increased.

Link: https://lore.kernel.org/r/20210227170006.5077-23-michael.christie@oracle.com


Signed-off-by: default avatarMike Christie <michael.christie@oracle.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 302990ac

drivers/target/target_core_iblock.c

+43 −1
Original line number Diff line number Diff line
@@ -61,9 +61,18 @@ static struct se_device *iblock_alloc_device(struct se_hba *hba, const char *nam 
		return NULL;

	}



	ib_dev->ibd_plug = kcalloc(nr_cpu_ids, sizeof(*ib_dev->ibd_plug),

				   GFP_KERNEL);

	if (!ib_dev->ibd_plug)

		goto free_dev;



	pr_debug( "IBLOCK: Allocated ib_dev for %s\n", name);



	return &ib_dev->dev;



free_dev:

	kfree(ib_dev);

	return NULL;

}



static int iblock_configure_device(struct se_device *dev)
@@ -171,6 +180,7 @@ static void iblock_dev_call_rcu(struct rcu_head *p) 
	struct se_device *dev = container_of(p, struct se_device, rcu_head);

	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);



	kfree(ib_dev->ibd_plug);

	kfree(ib_dev);

}
@@ -188,6 +198,33 @@ static void iblock_destroy_device(struct se_device *dev) 
	bioset_exit(&ib_dev->ibd_bio_set);

}



static struct se_dev_plug *iblock_plug_device(struct se_device *se_dev)

{

	struct iblock_dev *ib_dev = IBLOCK_DEV(se_dev);

	struct iblock_dev_plug *ib_dev_plug;



	/*

	 * Each se_device has a per cpu work this can be run from. Wwe

	 * shouldn't have multiple threads on the same cpu calling this

	 * at the same time.

	 */

	ib_dev_plug = &ib_dev->ibd_plug[smp_processor_id()];

	if (test_and_set_bit(IBD_PLUGF_PLUGGED, &ib_dev_plug->flags))

		return NULL;



	blk_start_plug(&ib_dev_plug->blk_plug);

	return &ib_dev_plug->se_plug;

}



static void iblock_unplug_device(struct se_dev_plug *se_plug)

{

	struct iblock_dev_plug *ib_dev_plug = container_of(se_plug,

					struct iblock_dev_plug, se_plug);



	blk_finish_plug(&ib_dev_plug->blk_plug);

	clear_bit(IBD_PLUGF_PLUGGED, &ib_dev_plug->flags);

}



static unsigned long long iblock_emulate_read_cap_with_block_size(

	struct se_device *dev,

	struct block_device *bd,
@@ -335,7 +372,10 @@ static void iblock_submit_bios(struct bio_list *list) 
{

	struct blk_plug plug;

	struct bio *bio;



	/*

	 * The block layer handles nested plugs, so just plug/unplug to handle

	 * fabric drivers that didn't support batching and multi bio cmds.

	 */

	blk_start_plug(&plug);

	while ((bio = bio_list_pop(list)))

		submit_bio(bio);
@@ -867,6 +907,8 @@ static const struct target_backend_ops iblock_ops = { 
	.configure_device	= iblock_configure_device,

	.destroy_device		= iblock_destroy_device,

	.free_device		= iblock_free_device,

	.plug_device		= iblock_plug_device,

	.unplug_device		= iblock_unplug_device,

	.parse_cdb		= iblock_parse_cdb,

	.set_configfs_dev_params = iblock_set_configfs_dev_params,

	.show_configfs_dev_params = iblock_show_configfs_dev_params,

drivers/target/target_core_iblock.h

+10 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 


#include <linux/atomic.h>

#include <linux/refcount.h>

#include <linux/blkdev.h>

#include <target/target_core_base.h>



#define IBLOCK_VERSION		"4.0"
@@ -17,6 +18,14 @@ struct iblock_req { 


#define IBDF_HAS_UDEV_PATH		0x01



#define IBD_PLUGF_PLUGGED		0x01



struct iblock_dev_plug {

	struct se_dev_plug se_plug;

	struct blk_plug blk_plug;

	unsigned long flags;

};



struct iblock_dev {

	struct se_device dev;

	unsigned char ibd_udev_path[SE_UDEV_PATH_LEN];
@@ -24,6 +33,7 @@ struct iblock_dev { 
	struct bio_set	ibd_bio_set;

	struct block_device *ibd_bd;

	bool ibd_readonly;

	struct iblock_dev_plug *ibd_plug;

} ____cacheline_aligned;



#endif /* TARGET_CORE_IBLOCK_H */