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scsi: target: iblock: Add backend plug/unplug callouts

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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: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Mike Christie 2021-02-27 11:00:03 -06:00 committed by Martin K. Petersen
parent 302990ac3b
commit 415ccd9811
2 changed files with 53 additions and 1 deletions
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44
drivers/target/target_core_iblock.c
View file

@ -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,

10
drivers/target/target_core_iblock.h
View file

@ -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 */