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Commit 1b7f390e authored by Asias He's avatar Asias He Committed by Nicholas Bellinger
Browse files

tcm_vhost: Multi-queue support 

This adds virtio-scsi multi-queue support to tcm_vhost. In order to use
multi-queue, guest side multi-queue support is need. It can
be found here:

   https://lkml.org/lkml/2012/12/18/166



Currently, only one thread is created by vhost core code for each
vhost_scsi instance. Even if there are multi-queues, all the handling of
guest kick (vhost_scsi_handle_kick) are processed in one thread. This is
not optimal. Luckily, most of the work is offloaded to the tcm_vhost
workqueue.

Some initial perf numbers:
1 queue,  4 targets, 1 lun per target
4K request size, 50% randread + 50% randwrite: 127K/127k IOPS

4 queues, 4 targets, 1 lun per target
4K request size, 50% randread + 50% randwrite: 181K/181k IOPS

Signed-off-by: default avatarAsias He <asias@redhat.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 67e18cf9

drivers/vhost/tcm_vhost.c

+29 −17
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ 
#include <linux/virtio_net.h> /* TODO vhost.h currently depends on this */

#include <linux/virtio_scsi.h>

#include <linux/llist.h>

#include <linux/bitmap.h>



#include "vhost.c"

#include "vhost.h"
@@ -60,6 +61,7 @@ enum { 
};



#define VHOST_SCSI_MAX_TARGET	256

#define VHOST_SCSI_MAX_VQ	128



struct vhost_scsi {

	/* Protected by vhost_scsi->dev.mutex */
@@ -68,7 +70,7 @@ struct vhost_scsi { 
	bool vs_endpoint;



	struct vhost_dev dev;

	struct vhost_virtqueue vqs[3];

	struct vhost_virtqueue vqs[VHOST_SCSI_MAX_VQ];



	struct vhost_work vs_completion_work; /* cmd completion work item */

	struct llist_head vs_completion_list; /* cmd completion queue */
@@ -366,12 +368,14 @@ static void vhost_scsi_complete_cmd_work(struct vhost_work *work) 
{

	struct vhost_scsi *vs = container_of(work, struct vhost_scsi,

					vs_completion_work);

	DECLARE_BITMAP(signal, VHOST_SCSI_MAX_VQ);

	struct virtio_scsi_cmd_resp v_rsp;

	struct tcm_vhost_cmd *tv_cmd;

	struct llist_node *llnode;

	struct se_cmd *se_cmd;

	int ret;

	int ret, vq;



	bitmap_zero(signal, VHOST_SCSI_MAX_VQ);

	llnode = llist_del_all(&vs->vs_completion_list);

	while (llnode) {

		tv_cmd = llist_entry(llnode, struct tcm_vhost_cmd,
@@ -390,15 +394,20 @@ static void vhost_scsi_complete_cmd_work(struct vhost_work *work) 
		memcpy(v_rsp.sense, tv_cmd->tvc_sense_buf,

		       v_rsp.sense_len);

		ret = copy_to_user(tv_cmd->tvc_resp, &v_rsp, sizeof(v_rsp));

		if (likely(ret == 0))

			vhost_add_used(&vs->vqs[2], tv_cmd->tvc_vq_desc, 0);

		else

		if (likely(ret == 0)) {

			vhost_add_used(tv_cmd->tvc_vq, tv_cmd->tvc_vq_desc, 0);

			vq = tv_cmd->tvc_vq - vs->vqs;

			__set_bit(vq, signal);

		} else

			pr_err("Faulted on virtio_scsi_cmd_resp\n");



		vhost_scsi_free_cmd(tv_cmd);

	}



	vhost_signal(&vs->dev, &vs->vqs[2]);

	vq = -1;

	while ((vq = find_next_bit(signal, VHOST_SCSI_MAX_VQ, vq + 1))

		< VHOST_SCSI_MAX_VQ)

		vhost_signal(&vs->dev, &vs->vqs[vq]);

}



static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd(
@@ -561,9 +570,9 @@ static void tcm_vhost_submission_work(struct work_struct *work) 
	}

}



static void vhost_scsi_handle_vq(struct vhost_scsi *vs)

static void vhost_scsi_handle_vq(struct vhost_scsi *vs,

	struct vhost_virtqueue *vq)

{

	struct vhost_virtqueue *vq = &vs->vqs[2];

	struct virtio_scsi_cmd_req v_req;

	struct tcm_vhost_tpg *tv_tpg;

	struct tcm_vhost_cmd *tv_cmd;
@@ -656,7 +665,7 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs) 
			ret = __copy_to_user(resp, &rsp, sizeof(rsp));

			if (!ret)

				vhost_add_used_and_signal(&vs->dev,

						&vs->vqs[2], head, 0);

							  vq, head, 0);

			else

				pr_err("Faulted on virtio_scsi_cmd_resp\n");
@@ -678,6 +687,7 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs) 
			": %d\n", tv_cmd, exp_data_len, data_direction);



		tv_cmd->tvc_vhost = vs;

		tv_cmd->tvc_vq = vq;



		if (unlikely(vq->iov[out].iov_len !=

				sizeof(struct virtio_scsi_cmd_resp))) {
@@ -758,7 +768,7 @@ static void vhost_scsi_handle_kick(struct vhost_work *work) 
						poll.work);

	struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev);



	vhost_scsi_handle_vq(vs);

	vhost_scsi_handle_vq(vs, vq);

}



/*
@@ -879,7 +889,7 @@ static int vhost_scsi_clear_endpoint( 
static int vhost_scsi_open(struct inode *inode, struct file *f)

{

	struct vhost_scsi *s;

	int r;

	int r, i;



	s = kzalloc(sizeof(*s), GFP_KERNEL);

	if (!s)
@@ -889,8 +899,9 @@ static int vhost_scsi_open(struct inode *inode, struct file *f) 


	s->vqs[VHOST_SCSI_VQ_CTL].handle_kick = vhost_scsi_ctl_handle_kick;

	s->vqs[VHOST_SCSI_VQ_EVT].handle_kick = vhost_scsi_evt_handle_kick;

	s->vqs[VHOST_SCSI_VQ_IO].handle_kick = vhost_scsi_handle_kick;

	r = vhost_dev_init(&s->dev, s->vqs, 3);

	for (i = VHOST_SCSI_VQ_IO; i < VHOST_SCSI_MAX_VQ; i++)

		s->vqs[i].handle_kick = vhost_scsi_handle_kick;

	r = vhost_dev_init(&s->dev, s->vqs, VHOST_SCSI_MAX_VQ);

	if (r < 0) {

		kfree(s);

		return r;
@@ -922,9 +933,10 @@ static void vhost_scsi_flush_vq(struct vhost_scsi *vs, int index) 


static void vhost_scsi_flush(struct vhost_scsi *vs)

{

	vhost_scsi_flush_vq(vs, VHOST_SCSI_VQ_CTL);

	vhost_scsi_flush_vq(vs, VHOST_SCSI_VQ_EVT);

	vhost_scsi_flush_vq(vs, VHOST_SCSI_VQ_IO);

	int i;



	for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)

		vhost_scsi_flush_vq(vs, i);

}



static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)

drivers/vhost/tcm_vhost.h

+2 −0
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ struct tcm_vhost_cmd { 
	struct virtio_scsi_cmd_resp __user *tvc_resp;

	/* Pointer to vhost_scsi for our device */

	struct vhost_scsi *tvc_vhost;

	/* Pointer to vhost_virtqueue for the cmd */

	struct vhost_virtqueue *tvc_vq;

	/* Pointer to vhost nexus memory */

	struct tcm_vhost_nexus *tvc_nexus;

	/* The TCM I/O descriptor that is accessed via container_of() */