Il 08/01/2013 01:12, Rusty Russell ha scritto:
>>> Unfortunately, that cannot work because not all architectures support
>>> chained scatterlists.
>>> >>
>>> >> WHAT? I can't figure out what an arch needs to do to support this?
>> >
>> > It needs to use the iterator functions in its DMA
Paolo Bonzini writes:
> Il 07/01/2013 01:02, Rusty Russell ha scritto:
>> Paolo Bonzini writes:
>>> Il 02/01/2013 06:03, Rusty Russell ha scritto:
Paolo Bonzini writes:
> The virtqueue_add_buf function has two limitations:
>
> 1) it requires the caller to provide all the buffers
Il 07/01/2013 01:02, Rusty Russell ha scritto:
> Paolo Bonzini writes:
>> Il 02/01/2013 06:03, Rusty Russell ha scritto:
>>> Paolo Bonzini writes:
The virtqueue_add_buf function has two limitations:
1) it requires the caller to provide all the buffers in a single call;
2)
Paolo Bonzini writes:
> Il 02/01/2013 06:03, Rusty Russell ha scritto:
>> Paolo Bonzini writes:
>>> 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 m
Wanlong Gao writes:
> On 01/02/2013 01:03 PM, Rusty Russell wrote:
>> Paolo Bonzini writes:
>>> 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
Il 02/01/2013 06:03, Rusty Russell ha scritto:
> Paolo Bonzini writes:
>> 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
On 01/02/2013 01:03 PM, Rusty Russell wrote:
> Paolo Bonzini writes:
>> 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
Paolo Bonzini writes:
> 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;
Chained scatterlists are a horr
On Wed, Dec 19, 2012 at 06:51:30PM +0200, Michael S. Tsirkin wrote:
> On Wed, Dec 19, 2012 at 01:04:08PM +0100, Paolo Bonzini wrote:
> > Il 19/12/2012 11:47, Stefan Hajnoczi ha scritto:
> > > On Tue, Dec 18, 2012 at 01:32:48PM +0100, Paolo Bonzini wrote:
> > >> +/**
> > >> + * virtqueue_start_buf -
On Wed, Dec 19, 2012 at 01:04:08PM +0100, Paolo Bonzini wrote:
> Il 19/12/2012 11:47, Stefan Hajnoczi ha scritto:
> > On Tue, Dec 18, 2012 at 01:32:48PM +0100, Paolo Bonzini wrote:
> >> +/**
> >> + * virtqueue_start_buf - start building buffer for the other end
> >> + * @vq: the struct virtqueue we
On Wed, Dec 19, 2012 at 1:04 PM, Paolo Bonzini wrote:
> Il 19/12/2012 11:47, Stefan Hajnoczi ha scritto:
>> On Tue, Dec 18, 2012 at 01:32:48PM +0100, Paolo Bonzini wrote:
>> What is the purpose of count_sg?
>
> It is needed to decide whether to use an indirect or a direct buffer.
> The idea is to
Il 19/12/2012 11:47, Stefan Hajnoczi ha scritto:
> On Tue, Dec 18, 2012 at 01:32:48PM +0100, Paolo Bonzini wrote:
>> +/**
>> + * virtqueue_start_buf - start building buffer for the other end
>> + * @vq: the struct virtqueue we're talking about.
>> + * @buf: a struct keeping the state of the buffer
On Tue, Dec 18, 2012 at 01:32:48PM +0100, Paolo Bonzini wrote:
> +/**
> + * virtqueue_start_buf - start building buffer for the other end
> + * @vq: the struct virtqueue we're talking about.
> + * @buf: a struct keeping the state of the buffer
> + * @data: the token identifying the buffer.
> + * @c
On Tue, Dec 18, 2012 at 03:32:15PM +0100, Paolo Bonzini wrote:
> Il 18/12/2012 14:59, Michael S. Tsirkin ha scritto:
> >>> Can't we track state internally to the virtqueue? Exposing it
> >>> seems to buy us nothing since you can't call add_buf between
> >>> start and end anyway.
> >>
> >> I wanted
Il 18/12/2012 14:59, Michael S. Tsirkin ha scritto:
>>> Can't we track state internally to the virtqueue? Exposing it
>>> seems to buy us nothing since you can't call add_buf between
>>> start and end anyway.
>>
>> I wanted to keep the state for these functions separate from the
>> rest. I don't t
On Tue, Dec 18, 2012 at 02:43:51PM +0100, Paolo Bonzini wrote:
> Il 18/12/2012 14:36, Michael S. Tsirkin ha scritto:
> > Some comments without arguing about whether the performance
> > benefit is worth it.
> >
> > On Tue, Dec 18, 2012 at 01:32:48PM +0100, Paolo Bonzini wrote:
> >> diff --git a/inc
Il 18/12/2012 14:36, Michael S. Tsirkin ha scritto:
> Some comments without arguing about whether the performance
> benefit is worth it.
>
> On Tue, Dec 18, 2012 at 01:32:48PM +0100, Paolo Bonzini wrote:
>> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
>> index cf8adb1..39d56c4 1006
Some comments without arguing about whether the performance
benefit is worth it.
On Tue, Dec 18, 2012 at 01:32:48PM +0100, Paolo Bonzini wrote:
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index cf8adb1..39d56c4 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio
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 reque
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