search for: vhost_set_vmap_dirty

On Thu, Mar 07, 2019 at 10:45:57AM +0800, Jason Wang wrote: > > On 2019/3/7 ??12:31, Michael S. Tsirkin wrote: > > > +static void vhost_set_vmap_dirty(struct vhost_vmap *used) > > > +{ > > > + int i; > > > + > > > + for (i = 0; i < used->npages; i++) > > > + set_page_dirty_lock(used->pages[i]); > > This seems to rely on page lock to mark page dirty. > > > > Could it happen...

On Thu, Mar 07, 2019 at 10:45:57AM +0800, Jason Wang wrote: > > On 2019/3/7 ??12:31, Michael S. Tsirkin wrote: > > > +static void vhost_set_vmap_dirty(struct vhost_vmap *used) > > > +{ > > > + int i; > > > + > > > + for (i = 0; i < used->npages; i++) > > > + set_page_dirty_lock(used->pages[i]); > > This seems to rely on page lock to mark page dirty. > > > > Could it happen...

...;num), false); > +} > + > +static int vhost_setup_used_vmap(struct vhost_virtqueue *vq, > + unsigned long used) > +{ > + return vhost_init_vmap(vq->dev, &vq->used_ring, used, > + vhost_get_used_size(vq, vq->num), true); > +} > + > +static void vhost_set_vmap_dirty(struct vhost_vmap *used) > +{ > + int i; > + > + for (i = 0; i < used->npages; i++) > + set_page_dirty_lock(used->pages[i]); This seems to rely on page lock to mark page dirty. Could it happen that page writeback will check the page, find it clean, and then you mark it d...

...;num), false); > +} > + > +static int vhost_setup_used_vmap(struct vhost_virtqueue *vq, > + unsigned long used) > +{ > + return vhost_init_vmap(vq->dev, &vq->used_ring, used, > + vhost_get_used_size(vq, vq->num), true); > +} > + > +static void vhost_set_vmap_dirty(struct vhost_vmap *used) > +{ > + int i; > + > + for (i = 0; i < used->npages; i++) > + set_page_dirty_lock(used->pages[i]); This seems to rely on page lock to mark page dirty. Could it happen that page writeback will check the page, find it clean, and then you mark it d...

On 2019/3/7 ??12:31, Michael S. Tsirkin wrote: >> +static void vhost_set_vmap_dirty(struct vhost_vmap *used) >> +{ >> + int i; >> + >> + for (i = 0; i < used->npages; i++) >> + set_page_dirty_lock(used->pages[i]); > This seems to rely on page lock to mark page dirty. > > Could it happen that page writeback will check the > page,...

...g, desc, + vhost_get_desc_size(vq, vq->num), false); +} + +static int vhost_setup_used_vmap(struct vhost_virtqueue *vq, + unsigned long used) +{ + return vhost_init_vmap(vq->dev, &vq->used_ring, used, + vhost_get_used_size(vq, vq->num), true); +} + +static void vhost_set_vmap_dirty(struct vhost_vmap *used) +{ + int i; + + for (i = 0; i < used->npages; i++) + set_page_dirty_lock(used->pages[i]); +} + void vhost_dev_cleanup(struct vhost_dev *dev) { int i; @@ -662,8 +815,12 @@ void vhost_dev_cleanup(struct vhost_dev *dev) kthread_stop(dev->worker); dev-&gt...

On Thu, Mar 07, 2019 at 10:34:39AM -0500, Michael S. Tsirkin wrote: > On Thu, Mar 07, 2019 at 10:45:57AM +0800, Jason Wang wrote: > > > > On 2019/3/7 ??12:31, Michael S. Tsirkin wrote: > > > > +static void vhost_set_vmap_dirty(struct vhost_vmap *used) > > > > +{ > > > > + int i; > > > > + > > > > + for (i = 0; i < used->npages; i++) > > > > + set_page_dirty_lock(used->pages[i]); > > > This seems to rely on page lock to mark page dirty. > &g...

This series tries to access virtqueue metadata through kernel virtual address instead of copy_user() friends since they had too much overheads like checks, spec barriers or even hardware feature toggling. This is done through setup kernel address through vmap() and resigter MMU notifier for invalidation. Test shows about 24% improvement on TX PPS. TCP_STREAM doesn't see obvious improvement.

This series tries to access virtqueue metadata through kernel virtual address instead of copy_user() friends since they had too much overheads like checks, spec barriers or even hardware feature toggling. This is done through setup kernel address through vmap() and resigter MMU notifier for invalidation. Test shows about 24% improvement on TX PPS. TCP_STREAM doesn't see obvious improvement.