On Wed, Dec 07, 2011 at 04:02:45PM +0200, Sasha Levin wrote: > On Sun, 2011-12-04 at 20:23 +0200, Sasha Levin wrote: > > [snip] > > Rusty, Michael, does the below looks a reasonable optimization for you? OK overall but a bit hard to say for sure as it looks pretty incomplete ... > should I send it as a patch? What's the performance gain? > > Something like the following patch: > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index c7a2c20..3166ca0 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -82,6 +82,7 @@ struct vring_virtqueue > > > > /* Host supports indirect buffers */ > > bool indirect; > > + struct kmem_cache *indirect_cache; > > > > /* Host publishes avail event idx */ > > bool event; > > @@ -110,6 +111,9 @@ struct vring_virtqueue > > > > #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq) > > > > +static unsigned int ind_alloc_thresh = 0; > > +module_param(ind_alloc_thresh, uint, S_IRUGO); 0 will have no effect? > > + > > /* Set up an indirect table of descriptors and add it to the queue. */ > > static int vring_add_indirect(struct vring_virtqueue *vq, > > struct scatterlist sg[], A global parameter is OK for testing but likely not what we want in real life. This needs to be different per device. > > @@ -121,7 +125,10 @@ 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) <= ind_alloc_thresh) > > + desc = kmem_cache_alloc(vq->indirect_cache, gfp); > > + else > > + desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp); > > if (!desc) > > return -ENOMEM; > > free unaffected? > > @@ -479,6 +486,9 @@ struct virtqueue *vring_new_virtqueue(unsigned int num, > > vq->broken = false; > > vq->last_used_idx = 0; > > vq->num_added = 0; > > + if (ind_alloc_thresh) > > + vq->indirect_cache = KMEM_CACHE(vring_desc[ind_alloc_thresh], 0); and need to cleanup too? > > list_add_tail(&vq->vq.list, &vdev->vqs); > > #ifdef DEBUG > > vq->in_use = false; > > > > -- > > Sasha. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
