On 2/4/21 03:40, Mike Christie wrote:
> This patch adds plug/unplug callouts for iblock. For initiator drivers
> 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.
>
> Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
> ---
> drivers/target/target_core_iblock.c | 41 ++++++++++++++++++++++++++++-
> drivers/target/target_core_iblock.h | 10 +++++++
> 2 files changed, 50 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
> index 8ed93fd205c7..a4951e662615 100644
> --- a/drivers/target/target_core_iblock.c
> +++ b/drivers/target/target_core_iblock.c
> @@ -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 +198,30 @@ 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_cmd *se_cmd)
> +{
> + struct se_device *se_dev = se_cmd->se_dev;
> + struct iblock_dev *ib_dev = IBLOCK_DEV(se_dev);
> + struct iblock_dev_plug *ib_dev_plug;
> +
> + ib_dev_plug = &ib_dev->ibd_plug[se_cmd->cpuid];
> + 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);
I think something like on the new line read much easier for me atleast :-
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,
> @@ -337,7 +371,10 @@ 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);
> @@ -870,6 +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,
> diff --git a/drivers/target/target_core_iblock.h b/drivers/target/target_core_iblock.h
> index cefc641145b3..8c55375d2f75 100644
> --- a/drivers/target/target_core_iblock.h
> +++ b/drivers/target/target_core_iblock.h
> @@ -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 */
