similar to: [PATCH] virtio: use chained scatterlists

Remove wrapper functions. This makes the allocation type explicit in all callers; I used GPF_KERNEL where it seemed obvious, left it at GFP_ATOMIC otherwise. Signed-off-by: Rusty Russell <rusty at rustcorp.com.au> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -171,7 +171,7 @@ static bool

Remove wrapper functions. This makes the allocation type explicit in all callers; I used GPF_KERNEL where it seemed obvious, left it at GFP_ATOMIC otherwise. Signed-off-by: Rusty Russell <rusty at rustcorp.com.au> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -171,7 +171,7 @@ static bool

This allows more requests to fit in the descriptor ring. Copying 1.7M 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().

This allows more requests to fit in the descriptor ring. Copying 1.7M 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().

On Fri, Sep 05, 2014 at 12:40:50PM +0200, Paolo Bonzini wrote: > Il 03/09/2014 06:29, Rusty Russell ha scritto: > > + sg_init_table(rq->sg, MAX_SKB_FRAGS + 2); > > I think 2 is enough here. That said... > > > sg_set_buf(rq->sg, &hdr->hdr, sizeof hdr->hdr); > > - > > skb_to_sgvec(skb, rq->sg + 1, 0, skb->len); > > > >

Il 03/09/2014 06:29, Rusty Russell ha scritto: > + sg_init_table(rq->sg, MAX_SKB_FRAGS + 2); I think 2 is enough here. That said... > sg_set_buf(rq->sg, &hdr->hdr, sizeof hdr->hdr); > - > skb_to_sgvec(skb, rq->sg + 1, 0, skb->len); > > err = virtqueue_add_inbuf(rq->vq, rq->sg, 2, skb, gfp); ... skb_to_sgvec will already make the sg well

Il 03/09/2014 06:29, Rusty Russell ha scritto: > + sg_init_table(rq->sg, MAX_SKB_FRAGS + 2); I think 2 is enough here. That said... > sg_set_buf(rq->sg, &hdr->hdr, sizeof hdr->hdr); > - > skb_to_sgvec(skb, rq->sg + 1, 0, skb->len); > > err = virtqueue_add_inbuf(rq->vq, rq->sg, 2, skb, gfp); ... skb_to_sgvec will already make the sg well

Add virtqueue_add_sgs which is more general than virtqueue_add_buf, which makes virtio-scsi and virtio-blk nicer, then add virtqueue_add_inbuf and virtqueue_add_outbuf which handle the more general case, and finally delete virtqueue_add_buf(). I'm hoping this will be the final post of the whole series, and it can move from my pending-rebases tree into virtio-next. Thanks! Rusty. Paolo

Add virtqueue_add_sgs which is more general than virtqueue_add_buf, which makes virtio-scsi and virtio-blk nicer, then add virtqueue_add_inbuf and virtqueue_add_outbuf which handle the more general case, and finally delete virtqueue_add_buf(). I'm hoping this will be the final post of the whole series, and it can move from my pending-rebases tree into virtio-next. Thanks! Rusty. Paolo

This API change means that virtio_net can tell how much capacity remains for buffers. It's necessarily fuzzy, since VIRTIO_RING_F_INDIRECT_DESC means we can fit any number of descriptors in one, *if* we can kmalloc. Signed-off-by: Rusty Russell <rusty at rustcorp.com.au> Cc: Dinesh Subhraveti <dineshs at us.ibm.com> --- drivers/block/virtio_blk.c | 2 +-

This API change means that virtio_net can tell how much capacity remains for buffers. It's necessarily fuzzy, since VIRTIO_RING_F_INDIRECT_DESC means we can fit any number of descriptors in one, *if* we can kmalloc. Signed-off-by: Rusty Russell <rusty at rustcorp.com.au> Cc: Dinesh Subhraveti <dineshs at us.ibm.com> --- drivers/block/virtio_blk.c | 2 +-

The virtqueue_add_buf function has two limitations: 1) it requires the caller to provide all the buffers in a single call; 2) it does not support chained scatterlists: the buffers must be provided as an array of struct scatterlist. Because of these limitations, virtio-scsi has to copy each request into a scatterlist internal to the driver. It cannot just use the one that was prepared by the

The virtqueue_add_buf function has two limitations: 1) it requires the caller to provide all the buffers in a single call; 2) it does not support chained scatterlists: the buffers must be provided as an array of struct scatterlist. Because of these limitations, virtio-scsi has to copy each request into a scatterlist internal to the driver. It cannot just use the one that was prepared by the

Most device drivers do not need to perform any postprocessing on the scatterlists they receive from higher-level drivers (e.g. the block or SCSI layer), because they translate the request metadata directly from the various C structs into the data that is required by the device. virtio devices however do this translation in two steps: a device-specific step in the device driver, and generic

Most device drivers do not need to perform any postprocessing on the scatterlists they receive from higher-level drivers (e.g. the block or SCSI layer), because they translate the request metadata directly from the various C structs into the data that is required by the device. virtio devices however do this translation in two steps: a device-specific step in the device driver, and generic

OK, this is (ab)uses some of Paolo's patches. The first 7 are candidates for this merge window (maybe), the rest I'm not so sure about. Thanks, Rusty. Paolo Bonzini (3): scatterlist: introduce sg_unmark_end virtio-blk: reorganize virtblk_add_req virtio-blk: use virtqueue_add_sgs on req path Rusty Russell (13): virtio_ring: virtqueue_add_sgs, to add multiple sgs. virtio-blk:

OK, this is (ab)uses some of Paolo's patches. The first 7 are candidates for this merge window (maybe), the rest I'm not so sure about. Thanks, Rusty. Paolo Bonzini (3): scatterlist: introduce sg_unmark_end virtio-blk: reorganize virtblk_add_req virtio-blk: use virtqueue_add_sgs on req path Rusty Russell (13): virtio_ring: virtqueue_add_sgs, to add multiple sgs. virtio-blk:

The virtio block device holds a lock during I/O request processing. Kicking the virtqueue while the lock is held results in long lock hold times and increases contention for the lock. This patch modifies virtqueue_kick() to optionally release a lock while notifying the host. Virtio block is modified to pass in its lock. This allows other vcpus to queue I/O requests during the time spent

The virtio block device holds a lock during I/O request processing. Kicking the virtqueue while the lock is held results in long lock hold times and increases contention for the lock. This patch modifies virtqueue_kick() to optionally release a lock while notifying the host. Virtio block is modified to pass in its lock. This allows other vcpus to queue I/O requests during the time spent

This patch adds support for an optional stats vq that works similary to the stats vq provided by virtio-balloon. The purpose of this change is to allow collection of statistics about working virtio-blk devices to easily analyze performance without having to tap into the guest. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: "Michael S. Tsirkin" <mst at redhat.com> Cc: