search for: blk_queue_max_hw_seg

...kernel image 100 times (with sync between) Before: totsegs = 55661 totlen = 148859962 avg. 2674 After: totsegs = 36097 totlen = 139439355 avg: 3862 Unfortunately, this coalescing is done at blk_rq_map_sg() which is too late to be optimal: requests have already been limited to the value set by blk_queue_max_hw_segments(). For us, that value reflects the number of sg slots we can handle (ie. after clustering). I suspect other drivers have the same issue. Jens? (This patch is a one liner + temporary stats-gathering cruft for show) Signed-off-by: Rusty Russell <rusty at rustcorp.com.au> --- drivers/...

...kernel image 100 times (with sync between) Before: totsegs = 55661 totlen = 148859962 avg. 2674 After: totsegs = 36097 totlen = 139439355 avg: 3862 Unfortunately, this coalescing is done at blk_rq_map_sg() which is too late to be optimal: requests have already been limited to the value set by blk_queue_max_hw_segments(). For us, that value reflects the number of sg slots we can handle (ie. after clustering). I suspect other drivers have the same issue. Jens? (This patch is a one liner + temporary stats-gathering cruft for show) Signed-off-by: Rusty Russell <rusty at rustcorp.com.au> --- drivers/...

....c +++ kvm/drivers/block/virtio_blk.c @@ -196,6 +196,7 @@ static int virtblk_probe(struct virtio_d int err; u64 cap; u32 v; + u64 blk_size; if (index_to_minor(index) >= 1 << MINORBITS) return -ENOSPC; @@ -290,6 +291,13 @@ static int virtblk_probe(struct virtio_d if (!err) blk_queue_max_hw_segments(vblk->disk->queue, v); + /* Host can optionally specify the block size of the device */ + err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, + offsetof(struct virtio_blk_config, blk_size), + &blk_size); + if (!err) + blk_queue_hardsect_size(vblk->disk->queue, blk_siz...

....c +++ kvm/drivers/block/virtio_blk.c @@ -196,6 +196,7 @@ static int virtblk_probe(struct virtio_d int err; u64 cap; u32 v; + u64 blk_size; if (index_to_minor(index) >= 1 << MINORBITS) return -ENOSPC; @@ -290,6 +291,13 @@ static int virtblk_probe(struct virtio_d if (!err) blk_queue_max_hw_segments(vblk->disk->queue, v); + /* Host can optionally specify the block size of the device */ + err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, + offsetof(struct virtio_blk_config, blk_size), + &blk_size); + if (!err) + blk_queue_hardsect_size(vblk->disk->queue, blk_siz...

...ror: dereferencing pointer to incomplete type drivers/block/lguest_blk.c:322: error: implicit declaration of function 'blk_init_queue' drivers/block/lguest_blk.c:323: error: dereferencing pointer to incomplete type drivers/block/lguest_blk.c:335: error: implicit declaration of function 'blk_queue_max_hw_segments' drivers/block/lguest_blk.c:335: error: dereferencing pointer to incomplete type drivers/block/lguest_blk.c:341: error: implicit declaration of function 'blk_queue_segment_boundary' drivers/block/lguest_blk.c:341: error: dereferencing pointer to incomplete type drivers/block/lguest...

...ror: dereferencing pointer to incomplete type drivers/block/lguest_blk.c:322: error: implicit declaration of function 'blk_init_queue' drivers/block/lguest_blk.c:323: error: dereferencing pointer to incomplete type drivers/block/lguest_blk.c:335: error: implicit declaration of function 'blk_queue_max_hw_segments' drivers/block/lguest_blk.c:335: error: dereferencing pointer to incomplete type drivers/block/lguest_blk.c:341: error: implicit declaration of function 'blk_queue_segment_boundary' drivers/block/lguest_blk.c:341: error: dereferencing pointer to incomplete type drivers/block/lguest...

...disk(1); + if (!bd->disk) { + err = -ENOMEM; + goto out_unregister_blkdev; + } + + bd->disk->queue = blk_init_queue(do_lgb_request, &bd->lock); + if (!bd->disk->queue) { + err = -ENOMEM; + goto out_put_disk; + } + + /* We can only handle a certain number of sg entries */ + blk_queue_max_hw_segments(bd->disk->queue, LGUEST_MAX_DMA_SECTIONS); + /* Buffers must not cross page boundaries */ + blk_queue_segment_boundary(bd->disk->queue, PAGE_SIZE-1); + + sprintf(bd->disk->disk_name, "lgb%c", next_block_index++); + if (lguest_devices[lgdev->index].features &...

...disk(1); + if (!bd->disk) { + err = -ENOMEM; + goto out_unregister_blkdev; + } + + bd->disk->queue = blk_init_queue(do_lgb_request, &bd->lock); + if (!bd->disk->queue) { + err = -ENOMEM; + goto out_put_disk; + } + + /* We can only handle a certain number of sg entries */ + blk_queue_max_hw_segments(bd->disk->queue, LGUEST_MAX_DMA_SECTIONS); + /* Buffers must not cross page boundaries */ + blk_queue_segment_boundary(bd->disk->queue, PAGE_SIZE-1); + + sprintf(bd->disk->disk_name, "lgb%c", next_block_index++); + if (lguest_devices[lgdev->index].features &...

...ev->config->find_vq(vdev, 0, blk_done); @@ -277,6 +289,13 @@ static int virtblk_probe(struct virtio_device *vdev) } set_capacity(vblk->disk, cap); + /* We can handle whatever the host told us to handle. */ + blk_queue_max_phys_segments(vblk->disk->queue, vblk->sg_elems-2); + blk_queue_max_hw_segments(vblk->disk->queue, vblk->sg_elems-2); + + /* No real sector limit. */ + blk_queue_max_sectors(vblk->disk->queue, -1U); + /* Host can optionally specify maximum segment size and number of * segments. */ err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, @@ -284,12 +303,8...

...ev->config->find_vq(vdev, 0, blk_done); @@ -277,6 +289,13 @@ static int virtblk_probe(struct virtio_device *vdev) } set_capacity(vblk->disk, cap); + /* We can handle whatever the host told us to handle. */ + blk_queue_max_phys_segments(vblk->disk->queue, vblk->sg_elems-2); + blk_queue_max_hw_segments(vblk->disk->queue, vblk->sg_elems-2); + + /* No real sector limit. */ + blk_queue_max_sectors(vblk->disk->queue, -1U); + /* Host can optionally specify maximum segment size and number of * segments. */ err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, @@ -284,12 +303,8...

This is a subject that came up in the virtio BOF session at OLS. I decided to go forward and implement something that I like, based on the latest virtio proposal at the time, which was draft III. It's not a drop-in replacement, because it's missing a host implementation. I first started my own, which is not done yet, but wanted to do one for lguest and one for emulated PCI next. It's

This is a subject that came up in the virtio BOF session at OLS. I decided to go forward and implement something that I like, based on the latest virtio proposal at the time, which was draft III. It's not a drop-in replacement, because it's missing a host implementation. I first started my own, which is not done yet, but wanted to do one for lguest and one for emulated PCI next. It's

In response to Avi's excellent analysis, I've updated virtio as promised (apologies for the delay, travel got in the way). === This attempts to implement a "virtual I/O" layer which should allow common drivers to be efficiently used across most virtual I/O mechanisms. It will no-doubt need further enhancement. The details of probing the device are left to hypervisor-specific

In response to Avi's excellent analysis, I've updated virtio as promised (apologies for the delay, travel got in the way). === This attempts to implement a "virtual I/O" layer which should allow common drivers to be efficiently used across most virtual I/O mechanisms. It will no-doubt need further enhancement. The details of probing the device are left to hypervisor-specific

This patch changes virtio_pci to use a shared memory area for virtio config info instead of using the PCI configuration space. This is closer semantically to what the virtio API exposes and is it a lot easier to implement on both ends. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c index eb9a8e0..7e6e453 100644

This patch changes virtio_pci to use a shared memory area for virtio config info instead of using the PCI configuration space. This is closer semantically to what the virtio API exposes and is it a lot easier to implement on both ends. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c index eb9a8e0..7e6e453 100644

Hi again all, It turns out that networking really wants ordered requests, which the previous patches didn't allow. This patch changes it to a callback mechanism; kudos to Avi. The downside is that locking is more complicated, and after a few dead ends I implemented the simplest solution: the struct virtio_device contains the spinlock to use, and it's held when your callbacks get

Hi again all, It turns out that networking really wants ordered requests, which the previous patches didn't allow. This patch changes it to a callback mechanism; kudos to Avi. The downside is that locking is more complicated, and after a few dead ends I implemented the simplest solution: the struct virtio_device contains the spinlock to use, and it's held when your callbacks get

Hi again all, It turns out that networking really wants ordered requests, which the previous patches didn't allow. This patch changes it to a callback mechanism; kudos to Avi. The downside is that locking is more complicated, and after a few dead ends I implemented the simplest solution: the struct virtio_device contains the spinlock to use, and it's held when your callbacks get

...onfig\n"); - goto out_cleanup_queue; - } - err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SEG_MAX, &v); + err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, + offsetof(struct virtio_blk_config, seg_max), + &v); if (!err) blk_queue_max_hw_segments(vblk->disk->queue, v); - else if (err != -ENOENT) { - dev_err(&vdev->dev, "Bad SEG_MAX in config\n"); - goto out_cleanup_queue; - } add_disk(vblk->disk); return 0; -out_cleanup_queue: - blk_cleanup_queue(vblk->disk->queue);...