On 01/18/2013 04:35 AM, Nicholas A. Bellinger wrote: > Hi Asias! > > On Sun, 2013-01-06 at 14:36 +0800, Asias He wrote: >> This drops the cmd completion list spin lock and makes the cmd >> completion queue lock-less. >> >> Signed-off-by: Asias He <[email protected]> >> --- > > Apologies for the long delay to get back to this patch.
No problem. > > After some initial testing, I'm seeing about about a ~5K IOPs > performance increase to single RAMDISK_MCP (~110K to ~115K) on the heavy > mixed 75/25 4k randrw fio workload. > That said, I think it's fine to as a for-3.9 item. Okay. > Acked-by: Nicholas Bellinger <[email protected]> > > MST, do you want to take this via your vhost tree, or shall I merge via > target-pending/for-next..? > > Thanks, > > --nab > >> drivers/vhost/tcm_vhost.c | 46 >> +++++++++++++--------------------------------- >> drivers/vhost/tcm_vhost.h | 2 +- >> 2 files changed, 14 insertions(+), 34 deletions(-) >> >> diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c >> index b20df5c..3720604 100644 >> --- a/drivers/vhost/tcm_vhost.c >> +++ b/drivers/vhost/tcm_vhost.c >> @@ -47,6 +47,7 @@ >> #include <linux/vhost.h> >> #include <linux/virtio_net.h> /* TODO vhost.h currently depends on this */ >> #include <linux/virtio_scsi.h> >> +#include <linux/llist.h> >> >> #include "vhost.c" >> #include "vhost.h" >> @@ -64,8 +65,7 @@ struct vhost_scsi { >> struct vhost_virtqueue vqs[3]; >> >> struct vhost_work vs_completion_work; /* cmd completion work item */ >> - struct list_head vs_completion_list; /* cmd completion queue */ >> - spinlock_t vs_completion_lock; /* protects s_completion_list */ >> + struct llist_head vs_completion_list; /* cmd completion queue */ >> }; >> >> /* Local pointer to allocated TCM configfs fabric module */ >> @@ -301,9 +301,7 @@ static void vhost_scsi_complete_cmd(struct tcm_vhost_cmd >> *tv_cmd) >> { >> struct vhost_scsi *vs = tv_cmd->tvc_vhost; >> >> - spin_lock_bh(&vs->vs_completion_lock); >> - list_add_tail(&tv_cmd->tvc_completion_list, &vs->vs_completion_list); >> - spin_unlock_bh(&vs->vs_completion_lock); >> + llist_add(&tv_cmd->tvc_completion_list, &vs->vs_completion_list); >> >> vhost_work_queue(&vs->dev, &vs->vs_completion_work); >> } >> @@ -347,27 +345,6 @@ static void vhost_scsi_free_cmd(struct tcm_vhost_cmd >> *tv_cmd) >> kfree(tv_cmd); >> } >> >> -/* Dequeue a command from the completion list */ >> -static struct tcm_vhost_cmd *vhost_scsi_get_cmd_from_completion( >> - struct vhost_scsi *vs) >> -{ >> - struct tcm_vhost_cmd *tv_cmd = NULL; >> - >> - spin_lock_bh(&vs->vs_completion_lock); >> - if (list_empty(&vs->vs_completion_list)) { >> - spin_unlock_bh(&vs->vs_completion_lock); >> - return NULL; >> - } >> - >> - list_for_each_entry(tv_cmd, &vs->vs_completion_list, >> - tvc_completion_list) { >> - list_del(&tv_cmd->tvc_completion_list); >> - break; >> - } >> - spin_unlock_bh(&vs->vs_completion_lock); >> - return tv_cmd; >> -} >> - >> /* Fill in status and signal that we are done processing this command >> * >> * This is scheduled in the vhost work queue so we are called with the owner >> @@ -377,12 +354,18 @@ static void vhost_scsi_complete_cmd_work(struct >> vhost_work *work) >> { >> struct vhost_scsi *vs = container_of(work, struct vhost_scsi, >> vs_completion_work); >> + struct virtio_scsi_cmd_resp v_rsp; >> struct tcm_vhost_cmd *tv_cmd; >> + struct llist_node *llnode; >> + struct se_cmd *se_cmd; >> + int ret; >> >> - while ((tv_cmd = vhost_scsi_get_cmd_from_completion(vs))) { >> - struct virtio_scsi_cmd_resp v_rsp; >> - struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd; >> - int ret; >> + llnode = llist_del_all(&vs->vs_completion_list); >> + while (llnode) { >> + tv_cmd = llist_entry(llnode, struct tcm_vhost_cmd, >> + tvc_completion_list); >> + llnode = llist_next(llnode); >> + se_cmd = &tv_cmd->tvc_se_cmd; >> >> pr_debug("%s tv_cmd %p resid %u status %#02x\n", __func__, >> tv_cmd, se_cmd->residual_count, se_cmd->scsi_status); >> @@ -426,7 +409,6 @@ static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd( >> pr_err("Unable to allocate struct tcm_vhost_cmd\n"); >> return ERR_PTR(-ENOMEM); >> } >> - INIT_LIST_HEAD(&tv_cmd->tvc_completion_list); >> tv_cmd->tvc_tag = v_req->tag; >> tv_cmd->tvc_task_attr = v_req->task_attr; >> tv_cmd->tvc_exp_data_len = exp_data_len; >> @@ -859,8 +841,6 @@ static int vhost_scsi_open(struct inode *inode, struct >> file *f) >> return -ENOMEM; >> >> vhost_work_init(&s->vs_completion_work, vhost_scsi_complete_cmd_work); >> - INIT_LIST_HEAD(&s->vs_completion_list); >> - spin_lock_init(&s->vs_completion_lock); >> >> 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; >> diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h >> index 7e87c63..47ee80b 100644 >> --- a/drivers/vhost/tcm_vhost.h >> +++ b/drivers/vhost/tcm_vhost.h >> @@ -34,7 +34,7 @@ struct tcm_vhost_cmd { >> /* Sense buffer that will be mapped into outgoing status */ >> unsigned char tvc_sense_buf[TRANSPORT_SENSE_BUFFER]; >> /* Completed commands list, serviced from vhost worker thread */ >> - struct list_head tvc_completion_list; >> + struct llist_node tvc_completion_list; >> }; >> >> struct tcm_vhost_nexus { > > -- Asias _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
