Re: [PATCH] tcm_vhost: Multi-queue support

[Asias He <asias@redhat.com>]

On 02/06/2013 02:45 PM, Nicholas A. Bellinger wrote:
> On Wed, 2013-02-06 at 13:20 +0800, Asias He wrote:
>> This adds virtio-scsi multi-queue support to tcm_vhost.
>>
>> Guest side virtio-scsi multi-queue support can be found here:
>>
>>    https://lkml.org/lkml/2012/12/18/166
>>
>> 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
>>
> 
> Nice single LUN small block random I/O improvement here with 4x vqueues.
> 
> Curious to see how virtio-scsi small block performance looks with
> SCSI-core to multi-LUN tcm_vhost endpoints as well..  8-)

Do you mean something like this?

1 queue,  2 targets, 2 lun per target
4 queue,  2 targets, 2 lun per target

> Btw, this does not apply atop current target-pending.git/for-next with
> your other pending vhost patch series, and AFAICT this patch is supposed
> to apply on top of your last PATCH-v3, no..?

Ah, this applies on top of mst's 'tcm_vhost: fix pr_err on early kick
patch.' plus my last v3 of 'tcm_vhost: Multi-target support'.

> --nab
> 
>> Signed-off-by: Asias He <asias@redhat.com>
>> ---
>>  drivers/vhost/tcm_vhost.c | 46 +++++++++++++++++++++++++++++-----------------
>>  drivers/vhost/tcm_vhost.h |  2 ++
>>  2 files changed, 31 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
>> index 81ecda5..9951297 100644
>> --- a/drivers/vhost/tcm_vhost.c
>> +++ b/drivers/vhost/tcm_vhost.c
>> @@ -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"
>> @@ -59,7 +60,8 @@ enum {
>>  	VHOST_SCSI_VQ_IO = 2,
>>  };
>>  
>> -#define VHOST_SCSI_MAX_TARGET 256
>> +#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 @@ err:
>>  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)
>> diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
>> index 519a550..1d2ae7a 100644
>> --- a/drivers/vhost/tcm_vhost.h
>> +++ b/drivers/vhost/tcm_vhost.h
>> @@ -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() */
> 
> 


-- 
Asias