From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755226Ab0FAJfS (ORCPT ); Tue, 1 Jun 2010 05:35:18 -0400 Received: from hera.kernel.org ([140.211.167.34]:40193 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752240Ab0FAJfO (ORCPT ); Tue, 1 Jun 2010 05:35:14 -0400 Message-ID: <4C04D41B.4050704@kernel.org> Date: Tue, 01 Jun 2010 11:34:19 +0200 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.1.9) Gecko/20100317 Thunderbird/3.0.4 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: Oleg Nesterov , Sridhar Samudrala , netdev , lkml , "kvm@vger.kernel.org" , Andrew Morton , Dmitri Vorobiev , Jiri Kosina , Thomas Gleixner , Ingo Molnar , Andi Kleen Subject: [PATCH 1/3] vhost: replace vhost_workqueue with per-vhost kthread References: <20100527163954.GA21710@redhat.com> <4BFEA434.6080405@kernel.org> <20100527173207.GA21880@redhat.com> <4BFEE216.2070807@kernel.org> <20100528150830.GB21880@redhat.com> <4BFFE742.2060205@kernel.org> <20100530112925.GB27611@redhat.com> <4C02C961.9050606@kernel.org> <20100531152221.GB2987@redhat.com> <4C03D983.9010905@kernel.org> <20100531160020.GC3067@redhat.com> In-Reply-To: <20100531160020.GC3067@redhat.com> X-Enigmail-Version: 1.0.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Tue, 01 Jun 2010 09:34:23 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Replace vhost_workqueue with per-vhost kthread. Other than callback argument change from struct work_struct * to struct vhost_work *, there's no visible change to vhost_poll_*() interface. This conversion is to make each vhost use a dedicated kthread so that resource control via cgroup can be applied. Partially based on Sridhar Samudrala's patch. * Updated to use sub structure vhost_work instead of directly using vhost_poll at Michael's suggestion. * Added flusher wake_up() optimization at Michael's suggestion. NOT_SIGNED_OFF_YET Cc: Michael S. Tsirkin Cc: Sridhar Samudrala --- Okay, here's the updated version. I'm still in the process of setting up the testing environment. I'll be traveling from this afternoon till tomorrow so I don't think I'll be able to test it before that. If you can give it a shot, it would be great. Thanks. drivers/vhost/net.c | 56 ++++++++++--------------- drivers/vhost/vhost.c | 110 ++++++++++++++++++++++++++++++++++++++------------ drivers/vhost/vhost.h | 38 +++++++++++------ 3 files changed, 133 insertions(+), 71 deletions(-) Index: work/drivers/vhost/net.c =================================================================== --- work.orig/drivers/vhost/net.c +++ work/drivers/vhost/net.c @@ -294,54 +294,58 @@ static void handle_rx(struct vhost_net * unuse_mm(net->dev.mm); } -static void handle_tx_kick(struct work_struct *work) +static void handle_tx_kick(struct vhost_work *work) { - struct vhost_virtqueue *vq; - struct vhost_net *net; - vq = container_of(work, struct vhost_virtqueue, poll.work); - net = container_of(vq->dev, struct vhost_net, dev); + struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue, + poll.work); + struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev); + handle_tx(net); } -static void handle_rx_kick(struct work_struct *work) +static void handle_rx_kick(struct vhost_work *work) { - struct vhost_virtqueue *vq; - struct vhost_net *net; - vq = container_of(work, struct vhost_virtqueue, poll.work); - net = container_of(vq->dev, struct vhost_net, dev); + struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue, + poll.work); + struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev); + handle_rx(net); } -static void handle_tx_net(struct work_struct *work) +static void handle_tx_net(struct vhost_work *work) { - struct vhost_net *net; - net = container_of(work, struct vhost_net, poll[VHOST_NET_VQ_TX].work); + struct vhost_net *net = container_of(work, struct vhost_net, + poll[VHOST_NET_VQ_TX].work); handle_tx(net); } -static void handle_rx_net(struct work_struct *work) +static void handle_rx_net(struct vhost_work *work) { - struct vhost_net *net; - net = container_of(work, struct vhost_net, poll[VHOST_NET_VQ_RX].work); + struct vhost_net *net = container_of(work, struct vhost_net, + poll[VHOST_NET_VQ_RX].work); handle_rx(net); } static int vhost_net_open(struct inode *inode, struct file *f) { struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL); + struct vhost_dev *dev; int r; + if (!n) return -ENOMEM; + + dev = &n->dev; n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick; n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick; - r = vhost_dev_init(&n->dev, n->vqs, VHOST_NET_VQ_MAX); + r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX); if (r < 0) { kfree(n); return r; } - vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT); - vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN); + vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev); + vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev); n->tx_poll_state = VHOST_NET_POLL_DISABLED; f->private_data = n; @@ -644,25 +648,13 @@ static struct miscdevice vhost_net_misc static int vhost_net_init(void) { - int r = vhost_init(); - if (r) - goto err_init; - r = misc_register(&vhost_net_misc); - if (r) - goto err_reg; - return 0; -err_reg: - vhost_cleanup(); -err_init: - return r; - + return misc_register(&vhost_net_misc); } module_init(vhost_net_init); static void vhost_net_exit(void) { misc_deregister(&vhost_net_misc); - vhost_cleanup(); } module_exit(vhost_net_exit); Index: work/drivers/vhost/vhost.c =================================================================== --- work.orig/drivers/vhost/vhost.c +++ work/drivers/vhost/vhost.c @@ -17,12 +17,12 @@ #include #include #include -#include #include #include #include #include #include +#include #include #include @@ -37,8 +37,6 @@ enum { VHOST_MEMORY_F_LOG = 0x1, }; -static struct workqueue_struct *vhost_workqueue; - static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh, poll_table *pt) { @@ -52,23 +50,31 @@ static void vhost_poll_func(struct file static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key) { - struct vhost_poll *poll; - poll = container_of(wait, struct vhost_poll, wait); + struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait); + if (!((unsigned long)key & poll->mask)) return 0; - queue_work(vhost_workqueue, &poll->work); + vhost_poll_queue(poll); return 0; } /* Init poll structure */ -void vhost_poll_init(struct vhost_poll *poll, work_func_t func, - unsigned long mask) +void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, + unsigned long mask, struct vhost_dev *dev) { - INIT_WORK(&poll->work, func); + struct vhost_work *work = &poll->work; + init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup); init_poll_funcptr(&poll->table, vhost_poll_func); poll->mask = mask; + poll->dev = dev; + + INIT_LIST_HEAD(&work->node); + work->fn = fn; + init_waitqueue_head(&work->done); + atomic_set(&work->flushing, 0); + work->queue_seq = work->done_seq = 0; } /* Start polling a file. We add ourselves to file's wait queue. The caller must @@ -92,12 +98,28 @@ void vhost_poll_stop(struct vhost_poll * * locks that are also used by the callback. */ void vhost_poll_flush(struct vhost_poll *poll) { - flush_work(&poll->work); + struct vhost_work *work = &poll->work; + int seq = work->queue_seq; + + atomic_inc(&work->flushing); + smp_mb__after_atomic_inc(); /* mb flush-b0 paired with worker-b1 */ + wait_event(work->done, seq - work->done_seq <= 0); + atomic_dec(&work->flushing); + smp_mb__after_atomic_dec(); /* rmb flush-b1 paired with worker-b0 */ } void vhost_poll_queue(struct vhost_poll *poll) { - queue_work(vhost_workqueue, &poll->work); + struct vhost_dev *dev = poll->dev; + struct vhost_work *work = &poll->work; + + spin_lock(&dev->work_lock); + if (list_empty(&work->node)) { + list_add_tail(&work->node, &dev->work_list); + work->queue_seq++; + wake_up_process(dev->worker); + } + spin_unlock(&dev->work_lock); } static void vhost_vq_reset(struct vhost_dev *dev, @@ -125,10 +147,52 @@ static void vhost_vq_reset(struct vhost_ vq->log_ctx = NULL; } +static int vhost_worker(void *data) +{ + struct vhost_dev *dev = data; + struct vhost_work *work; + +repeat: + set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ + + if (kthread_should_stop()) { + __set_current_state(TASK_RUNNING); + return 0; + } + + work = NULL; + spin_lock(&dev->work_lock); + if (!list_empty(&dev->work_list)) { + work = list_first_entry(&dev->work_list, + struct vhost_work, node); + list_del_init(&work->node); + } + spin_unlock(&dev->work_lock); + + if (work) { + __set_current_state(TASK_RUNNING); + work->fn(work); + smp_wmb(); /* wmb worker-b0 paired with flush-b1 */ + work->done_seq = work->queue_seq; + smp_mb(); /* mb worker-b1 paired with flush-b0 */ + if (atomic_read(&work->flushing)) + wake_up_all(&work->done); + } else + schedule(); + + goto repeat; +} + long vhost_dev_init(struct vhost_dev *dev, struct vhost_virtqueue *vqs, int nvqs) { + struct task_struct *worker; int i; + + worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid); + if (IS_ERR(worker)) + return PTR_ERR(worker); + dev->vqs = vqs; dev->nvqs = nvqs; mutex_init(&dev->mutex); @@ -136,6 +200,9 @@ long vhost_dev_init(struct vhost_dev *de dev->log_file = NULL; dev->memory = NULL; dev->mm = NULL; + spin_lock_init(&dev->work_lock); + INIT_LIST_HEAD(&dev->work_list); + dev->worker = worker; for (i = 0; i < dev->nvqs; ++i) { dev->vqs[i].dev = dev; @@ -143,9 +210,10 @@ long vhost_dev_init(struct vhost_dev *de vhost_vq_reset(dev, dev->vqs + i); if (dev->vqs[i].handle_kick) vhost_poll_init(&dev->vqs[i].poll, - dev->vqs[i].handle_kick, - POLLIN); + dev->vqs[i].handle_kick, POLLIN, dev); } + + wake_up_process(worker); /* avoid contributing to loadavg */ return 0; } @@ -217,6 +285,9 @@ void vhost_dev_cleanup(struct vhost_dev if (dev->mm) mmput(dev->mm); dev->mm = NULL; + + WARN_ON(!list_empty(&dev->work_list)); + kthread_stop(dev->worker); } static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz) @@ -1113,16 +1184,3 @@ void vhost_disable_notify(struct vhost_v vq_err(vq, "Failed to enable notification at %p: %d\n", &vq->used->flags, r); } - -int vhost_init(void) -{ - vhost_workqueue = create_singlethread_workqueue("vhost"); - if (!vhost_workqueue) - return -ENOMEM; - return 0; -} - -void vhost_cleanup(void) -{ - destroy_workqueue(vhost_workqueue); -} Index: work/drivers/vhost/vhost.h =================================================================== --- work.orig/drivers/vhost/vhost.h +++ work/drivers/vhost/vhost.h @@ -5,13 +5,13 @@ #include #include #include -#include #include #include #include #include #include #include +#include struct vhost_device; @@ -20,19 +20,31 @@ enum { VHOST_NET_MAX_SG = MAX_SKB_FRAGS + 2, }; +struct vhost_work; +typedef void (*vhost_work_fn_t)(struct vhost_work *work); + +struct vhost_work { + struct list_head node; + vhost_work_fn_t fn; + wait_queue_head_t done; + atomic_t flushing; + int queue_seq; + int done_seq; +}; + /* Poll a file (eventfd or socket) */ /* Note: there's nothing vhost specific about this structure. */ struct vhost_poll { poll_table table; wait_queue_head_t *wqh; wait_queue_t wait; - /* struct which will handle all actual work. */ - struct work_struct work; + struct vhost_work work; unsigned long mask; + struct vhost_dev *dev; }; -void vhost_poll_init(struct vhost_poll *poll, work_func_t func, - unsigned long mask); +void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, + unsigned long mask, struct vhost_dev *dev); void vhost_poll_start(struct vhost_poll *poll, struct file *file); void vhost_poll_stop(struct vhost_poll *poll); void vhost_poll_flush(struct vhost_poll *poll); @@ -63,7 +75,7 @@ struct vhost_virtqueue { struct vhost_poll poll; /* The routine to call when the Guest pings us, or timeout. */ - work_func_t handle_kick; + vhost_work_fn_t handle_kick; /* Last available index we saw. */ u16 last_avail_idx; @@ -86,11 +98,11 @@ struct vhost_virtqueue { struct iovec hdr[VHOST_NET_MAX_SG]; size_t hdr_size; /* We use a kind of RCU to access private pointer. - * All readers access it from workqueue, which makes it possible to - * flush the workqueue instead of synchronize_rcu. Therefore readers do + * All readers access it from worker, which makes it possible to + * flush the vhost_work instead of synchronize_rcu. Therefore readers do * not need to call rcu_read_lock/rcu_read_unlock: the beginning of - * work item execution acts instead of rcu_read_lock() and the end of - * work item execution acts instead of rcu_read_lock(). + * vhost_work execution acts instead of rcu_read_lock() and the end of + * vhost_work execution acts instead of rcu_read_lock(). * Writers use virtqueue mutex. */ void *private_data; /* Log write descriptors */ @@ -110,6 +122,9 @@ struct vhost_dev { int nvqs; struct file *log_file; struct eventfd_ctx *log_ctx; + spinlock_t work_lock; + struct list_head work_list; + struct task_struct *worker; }; long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs); @@ -136,9 +151,6 @@ bool vhost_enable_notify(struct vhost_vi int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, unsigned int log_num, u64 len); -int vhost_init(void); -void vhost_cleanup(void); - #define vq_err(vq, fmt, ...) do { \ pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \ if ((vq)->error_ctx) \