From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753980Ab2H2PhE (ORCPT ); Wed, 29 Aug 2012 11:37:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:20684 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751658Ab2H2PhA (ORCPT ); Wed, 29 Aug 2012 11:37:00 -0400 Date: Wed, 29 Aug 2012 18:38:12 +0300 From: "Michael S. Tsirkin" To: Sasha Levin Cc: rusty@rustcorp.com.au, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, avi@redhat.com, kvm@vger.kernel.org Subject: Re: [PATCH v2 2/2] virtio-ring: Allocate indirect buffers from cache when possible Message-ID: <20120829153812.GD7407@redhat.com> References: <1346159043-16446-1-git-send-email-levinsasha928@gmail.com> <1346159043-16446-2-git-send-email-levinsasha928@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1346159043-16446-2-git-send-email-levinsasha928@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 28, 2012 at 03:04:03PM +0200, Sasha Levin wrote: > Currently if VIRTIO_RING_F_INDIRECT_DESC is enabled we will > use indirect descriptors and allocate them using a simple > kmalloc(). > > This patch adds a cache which will allow indirect buffers under > a configurable size to be allocated from that cache instead. > > Signed-off-by: Sasha Levin The API is ugly - how does driver know what to set? Is this a typical request size? Then let's call it that. Also this is really per VQ, right? What is a good default for net? I guess max sg? > --- > > Changes in v2: > > - Free correctly indirect buffers. > > drivers/block/virtio_blk.c | 4 ++++ > drivers/char/hw_random/virtio-rng.c | 4 ++++ > drivers/char/virtio_console.c | 4 ++++ > drivers/net/virtio_net.c | 4 ++++ > drivers/virtio/virtio_balloon.c | 4 ++++ > drivers/virtio/virtio_ring.c | 28 ++++++++++++++++++++++++---- > include/linux/virtio.h | 1 + > net/9p/trans_virtio.c | 5 +++++ > 8 files changed, 50 insertions(+), 4 deletions(-) > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > index 13b8ae9..7f670af 100644 > --- a/drivers/block/virtio_blk.c > +++ b/drivers/block/virtio_blk.c > @@ -25,6 +25,9 @@ struct workqueue_struct *virtblk_wq; > static unsigned int indirect_thresh; > module_param(indirect_thresh, uint, S_IRUGO); > > +static unsigned int indirect_alloc_thresh; > +module_param(indirect_alloc_thresh, uint, S_IRUGO); > + > struct virtio_blk > { > struct virtio_device *vdev; > @@ -739,6 +742,7 @@ static int __devinit virtblk_probe(struct virtio_device *vdev) > INIT_WORK(&vblk->config_work, virtblk_config_changed_work); > vblk->config_enable = true; > vdev->indirect_thresh = indirect_thresh; > + vdev->indirect_alloc_thresh = indirect_alloc_thresh; > > err = init_vq(vblk); > if (err) > diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c > index 02d8421..8475ece 100644 > --- a/drivers/char/hw_random/virtio-rng.c > +++ b/drivers/char/hw_random/virtio-rng.c > @@ -28,6 +28,9 @@ > static unsigned int indirect_thresh; > module_param(indirect_thresh, uint, S_IRUGO); > > +static unsigned int indirect_alloc_thresh; > +module_param(indirect_alloc_thresh, uint, S_IRUGO); > + > static struct virtqueue *vq; > static unsigned int data_avail; > static DECLARE_COMPLETION(have_data); > @@ -97,6 +100,7 @@ static int probe_common(struct virtio_device *vdev) > > /* We expect a single virtqueue. */ > vdev->indirect_thresh = indirect_thresh; > + vdev->indirect_alloc_thresh = indirect_alloc_thresh; > vq = virtio_find_single_vq(vdev, random_recv_done, "input"); > if (IS_ERR(vq)) > return PTR_ERR(vq); > diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c > index fc14e7f..c6f24a7 100644 > --- a/drivers/char/virtio_console.c > +++ b/drivers/char/virtio_console.c > @@ -42,6 +42,9 @@ > static unsigned int indirect_thresh; > module_param(indirect_thresh, uint, S_IRUGO); > > +static unsigned int indirect_alloc_thresh; > +module_param(indirect_alloc_thresh, uint, S_IRUGO); > + > /* > * This is a global struct for storing common data for all the devices > * this driver handles. > @@ -1891,6 +1894,7 @@ static int __devinit virtcons_probe(struct virtio_device *vdev) > &portdev->config.max_nr_ports) == 0) > multiport = true; > vdev->indirect_thresh = indirect_thresh; > + vdev->indirect_alloc_thresh = indirect_alloc_thresh; > > err = init_vqs(portdev); > if (err < 0) { > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 64a8321..c091efd 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -37,6 +37,9 @@ module_param(gso, bool, 0444); > static unsigned int indirect_thresh; > module_param(indirect_thresh, uint, S_IRUGO); > > +static unsigned int indirect_alloc_thresh; > +module_param(indirect_alloc_thresh, uint, S_IRUGO); > + > /* FIXME: MTU in config. */ > #define MAX_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN) > #define GOOD_COPY_LEN 128 > @@ -1132,6 +1135,7 @@ static int virtnet_probe(struct virtio_device *vdev) > if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF)) > vi->mergeable_rx_bufs = true; > vdev->indirect_thresh = indirect_thresh; > + vdev->indirect_alloc_thresh = indirect_alloc_thresh; > > err = init_vqs(vi); > if (err) > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index fce7347..ccf87db 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -38,6 +38,9 @@ > static unsigned int indirect_thresh; > module_param(indirect_thresh, uint, S_IRUGO); > > +static unsigned int indirect_alloc_thresh; > +module_param(indirect_alloc_thresh, uint, S_IRUGO); > + > struct virtio_balloon > { > struct virtio_device *vdev; > @@ -360,6 +363,7 @@ static int virtballoon_probe(struct virtio_device *vdev) > vb->vdev = vdev; > vb->need_stats_update = 0; > vdev->indirect_thresh = indirect_thresh; > + vdev->indirect_alloc_thresh = indirect_alloc_thresh; > > err = init_vqs(vb); > if (err) > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 99a64a7..e8b9c54 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -93,6 +93,10 @@ struct vring_virtqueue > */ > unsigned int indirect_thresh; > > + /* Buffers below this size will be allocated from cache */ > + unsigned int indirect_alloc_thresh; > + struct kmem_cache *indirect_cache; > + > /* Host publishes avail event idx */ > bool event; > > @@ -135,7 +139,10 @@ static int vring_add_indirect(struct vring_virtqueue *vq, > unsigned head; > int i; > > - desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp); > + if ((out + in) <= vq->indirect_alloc_thresh) > + desc = kmem_cache_alloc(vq->indirect_cache, gfp); > + else > + desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp); > if (!desc) > return -ENOMEM; So this means that drivers need to know how large each descriptor is to avoid trying to allocate 32Mbyte chunks :) > > @@ -384,8 +391,13 @@ static void detach_buf(struct vring_virtqueue *vq, unsigned int head) > i = head; > > /* Free the indirect table */ > - if (vq->vring.desc[i].flags & VRING_DESC_F_INDIRECT) > - kfree(phys_to_virt(vq->vring.desc[i].addr)); > + if (vq->vring.desc[i].flags & VRING_DESC_F_INDIRECT) { > + if (vq->vring.desc[i].len > vq->indirect_alloc_thresh) This looks wrong. indirect_alloc_thresh is in entries but len is in bytes, isn't it? > + kfree(phys_to_virt(vq->vring.desc[i].addr)); > + else > + kmem_cache_free(vq->indirect_cache, > + phys_to_virt(vq->vring.desc[i].addr)); > + } > > while (vq->vring.desc[i].flags & VRING_DESC_F_NEXT) { > i = vq->vring.desc[i].next; > @@ -654,14 +666,20 @@ struct virtqueue *vring_new_virtqueue(unsigned int num, > vq->last_used_idx = 0; > vq->num_added = 0; > vq->indirect_thresh = 0; > + vq->indirect_alloc_thresh = 0; > + vq->indirect_cache = NULL; > list_add_tail(&vq->vq.list, &vdev->vqs); > #ifdef DEBUG > vq->in_use = false; > vq->last_add_time_valid = false; > #endif > > - if (virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)) > + if (virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)) { > vq->indirect_thresh = vdev->indirect_thresh; > + vq->indirect_alloc_thresh = vdev->indirect_alloc_thresh; > + if (vq->indirect_alloc_thresh) > + vq->indirect_cache = KMEM_CACHE(vring_desc[vq->indirect_alloc_thresh], > 0); I am not a purist but this line looks way too long. Also - no need to check cache creation succeeded? On failure - disable caching? Also - let's check that values are sane before passing them on? They come from user after all. Also - should not threshold be per VQ? E.g. for -net we do not need the cache for RX unless in legacy big packet mode. > + } > > vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX); > > @@ -685,6 +703,8 @@ EXPORT_SYMBOL_GPL(vring_new_virtqueue); > void vring_del_virtqueue(struct virtqueue *vq) > { > list_del(&vq->list); > + if (to_vvq(vq)->indirect_cache) > + kmem_cache_destroy(to_vvq(vq)->indirect_cache); > kfree(to_vvq(vq)); > } > EXPORT_SYMBOL_GPL(vring_del_virtqueue); > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index 48bc457..3261c02 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -70,6 +70,7 @@ struct virtio_device { > unsigned long features[1]; > void *priv; > unsigned int indirect_thresh; > + unsigned int indirect_alloc_thresh; > }; > > #define dev_to_virtio(dev) container_of(dev, struct virtio_device, dev) > diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c > index fc93962..3044c86 100644 > --- a/net/9p/trans_virtio.c > +++ b/net/9p/trans_virtio.c > @@ -55,6 +55,9 @@ > static unsigned int indirect_thresh; > module_param(indirect_thresh, uint, S_IRUGO); > > +static unsigned int indirect_alloc_thresh; > +module_param(indirect_alloc_thresh, uint, S_IRUGO); > + > /* a single mutex to manage channel initialization and attachment */ > static DEFINE_MUTEX(virtio_9p_lock); > static DECLARE_WAIT_QUEUE_HEAD(vp_wq); > @@ -505,6 +508,8 @@ static int p9_virtio_probe(struct virtio_device *vdev) > > /* We expect one virtqueue, for requests. */ > vdev->indirect_thresh = indirect_thresh; > + vdev->indirect_alloc_thresh = indirect_alloc_thresh; > + > chan->vq = virtio_find_single_vq(vdev, req_done, "requests"); > if (IS_ERR(chan->vq)) { > err = PTR_ERR(chan->vq); > -- > 1.7.12