search for: virtqueue_add_buf

...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 do_req(struct request_queue } } - if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr) < 0) { + if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr, GFP_ATOMIC)<0) { mempool_free(vbr, vblk->pool); return false; } diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c --- a/drivers/char/h...

...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 do_req(struct request_queue } } - if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr) < 0) { + if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr, GFP_ATOMIC)<0) { mempool_free(vbr, vblk->pool); return false; } diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c --- a/drivers/char/h...

Hi Rusty, The linux-next kernel was failing my virtio-console test suite for a while. I looked into it today, and it's due to the virtqueue_add_buf() change that doesn't return > 0 values anymore. I found your commit that adjusts virtio_console.c, but you missed one instance where the return value mattered, and as a result not enough buffers were queued for the host to send in data. This resulted in the port's name to be not popul...

Hi Rusty, The linux-next kernel was failing my virtio-console test suite for a while. I looked into it today, and it's due to the virtqueue_add_buf() change that doesn't return > 0 values anymore. I found your commit that adjusts virtio_console.c, but you missed one instance where the return value mattered, and as a result not enough buffers were queued for the host to send in data. This resulted in the port's name to be not popul...

Rather than handing a scatterlist[] and out and in numbers to virtqueue_add_buf(), hand two separate ones which can be chained. I shall refrain from ranting about what a disgusting hack chained scatterlists are. I'll just note that this doesn't make things simpler (see diff). The scatterlists we use can be too large for the stack, so we put them in our device struct...

Rather than handing a scatterlist[] and out and in numbers to virtqueue_add_buf(), hand two separate ones which can be chained. I shall refrain from ranting about what a disgusting hack chained scatterlists are. I'll just note that this doesn't make things simpler (see diff). The scatterlists we use can be too large for the stack, so we put them in our device struct...

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-...

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-...

...ayer), 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 preparation of virtio direct or indirect buffers in virtqueue_add_buf. Now, virtqueue_add_buf also accepts the outcome of the first step as a struct scatterlist, hence the drivers may need to put additional items at the front or back of the data scatterlists. On top of this, virtqueue_add_buf also has the limitation of not supporting chained scatterlists: the buffe...

...ayer), 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 preparation of virtio direct or indirect buffers in virtqueue_add_buf. Now, virtqueue_add_buf also accepts the outcome of the first step as a struct scatterlist, hence the drivers may need to put additional items at the front or back of the data scatterlists. On top of this, virtqueue_add_buf also has the limitation of not supporting chained scatterlists: the buffe...

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...

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...

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:

Hi Everybody, How to simulate the export function "virtqueue_add_buf"? I tried to invoke it by pinging to the host machine, but failed. Awaiting your replies ! Regards, Devi.

Hi Everybody, How to simulate the export function "virtqueue_add_buf"? I tried to invoke it by pinging to the host machine, but failed. Awaiting your replies ! Regards, Devi.

A virtio driver does virtqueue_add_buf() multiple times before finally calling virtqueue_kick(); previously we only exposed the added buffers in the virtqueue_kick() call. This means we don't need a memory barrier in virtqueue_add_buf(), but it reduces concurrency as the device (ie. host) can't see the buffers until the kick....

A virtio driver does virtqueue_add_buf() multiple times before finally calling virtqueue_kick(); previously we only exposed the added buffers in the virtqueue_kick() call. This means we don't need a memory barrier in virtqueue_add_buf(), but it reduces concurrency as the device (ie. host) can't see the buffers until the kick....

OK, so I've spent a few days benchmarking. Turns out 80% of virtio_add_buf cases are uni-directional (including the always-performance-sensitive networking code), and that gets no performance penalty (though tests with real networking would be appreciated!). I'm not reposting all the "convert driver to virtio_add_outbuf()" patches: just the scsi one which I didn't have

OK, so I've spent a few days benchmarking. Turns out 80% of virtio_add_buf cases are uni-directional (including the always-performance-sensitive networking code), and that gets no performance penalty (though tests with real networking would be appreciated!). I'm not reposting all the "convert driver to virtio_add_outbuf()" patches: just the scsi one which I didn't have