Re: [PATCH] tcm_vhost: Multi-queue support

[Asias He <asias@redhat.com>]

On 02/06/2013 04:39 PM, Nicholas A. Bellinger wrote:
> On Wed, 2013-02-06 at 15:09 +0800, Asias He wrote:
>> 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'.
>>
> 
> In that case, applying this patch + PATCH-v3 to auto-next for testing
> for the moment, and will respin for-next against upstream w/ MST's patch
> shortly.

Okay. Looking forward to more perf numbers.

> Also, please include a proper changelog for this second patch.  :)

Sure.

---->

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: Asias He <asias@redhat.com>

<----

> Thank you!
> 
> --nab
> 
> 
> 
>>> --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