search for: desc_wrap

Get it now. Please correct me if I missing something. Flags status hints, - DESC_DRIVER only: driver owns the descriptor w/o available info ready for device to use - DESC_DRIVER | DESC_WRAP: driver has prepared an available descriptor, device hasn't used it yet - None: device has used the descriptor, and write descriptor out - DESC_WRAP only: shall not happen, device make sure to clear it Polling behavior is, - Device monitor DESC_WRAP bit set or not; If set, go to use descri...

Get it now. Please correct me if I missing something. Flags status hints, - DESC_DRIVER only: driver owns the descriptor w/o available info ready for device to use - DESC_DRIVER | DESC_WRAP: driver has prepared an available descriptor, device hasn't used it yet - None: device has used the descriptor, and write descriptor out - DESC_WRAP only: shall not happen, device make sure to clear it Polling behavior is, - Device monitor DESC_WRAP bit set or not; If set, go to use descri...

...9:44:35AM +0000, Liang, Cunming wrote: >> >> Get it now. Please correct me if I missing something. >> >> >> Flags status hints, >> >> - DESC_DRIVER only: driver owns the descriptor w/o available info ready for device to use >> >> - DESC_DRIVER | DESC_WRAP: driver has prepared an available descriptor, device hasn't used it yet >> >> - None: device has used the descriptor, and write descriptor out >> >> - DESC_WRAP only: shall not happen, device make sure to clear it >> >> >> Polling behavior is, >>...

...9:44:35AM +0000, Liang, Cunming wrote: >> >> Get it now. Please correct me if I missing something. >> >> >> Flags status hints, >> >> - DESC_DRIVER only: driver owns the descriptor w/o available info ready for device to use >> >> - DESC_DRIVER | DESC_WRAP: driver has prepared an available descriptor, device hasn't used it yet >> >> - None: device has used the descriptor, and write descriptor out >> >> - DESC_WRAP only: shall not happen, device make sure to clear it >> >> >> Polling behavior is, >>...

Michael, Would you please give an example or two how these two flags DESC_DRIVER and DESC_WRAP are used together? Like others, I am confused by the description and still don?t quite grok it. Steven On 9/25/17, 3:24 PM, "virtio-dev at lists.oasis-open.org on behalf of Michael S. Tsirkin" <virtio-dev at lists.oasis-open.org on behalf of mst at redhat.com> wrote: On Wed,...

...tors, and not all descriptors have to be written out. > > > > Driver and device are expected to maintain (internally) a wrap-around bit, > > starting at 0 and changing value each time they start writing out descriptors > > at the beginning of the ring. This bit is passed as DESC_WRAP bit in the flags > > field. > > One simple question there, trying to understand the usage of DESC_WRAP flag. > > DESC_WRAP bit is a new flag since v2. It's used to address 'non power-of-2 ring sizes' mentioned in v2? > > Being confused by the statement of wrap...

...tors, and not all descriptors have to be written out. > > > > Driver and device are expected to maintain (internally) a wrap-around bit, > > starting at 0 and changing value each time they start writing out descriptors > > at the beginning of the ring. This bit is passed as DESC_WRAP bit in the flags > > field. > > One simple question there, trying to understand the usage of DESC_WRAP flag. > > DESC_WRAP bit is a new flag since v2. It's used to address 'non power-of-2 ring sizes' mentioned in v2? > > Being confused by the statement of wrap...

...ng something. > > > > > > > > > > > > Flags status hints, > > > > > > > > - DESC_DRIVER only: driver owns the descriptor w/o available info > > > > ready for device to use > > > > > > > > - DESC_DRIVER | DESC_WRAP: driver has prepared an available > > > > descriptor, device hasn't used it yet > > > > > > > > - None: device has used the descriptor, and write descriptor out > > > > > > > > - DESC_WRAP only: shall not happen, device make sure to cl...

...ng something. > > > > > > > > > > > > Flags status hints, > > > > > > > > - DESC_DRIVER only: driver owns the descriptor w/o available info > > > > ready for device to use > > > > > > > > - DESC_DRIVER | DESC_WRAP: driver has prepared an available > > > > descriptor, device hasn't used it yet > > > > > > > > - None: device has used the descriptor, and write descriptor out > > > > > > > > - DESC_WRAP only: shall not happen, device make sure to cl...

On Thu, Sep 28, 2017 at 09:44:35AM +0000, Liang, Cunming wrote: > > Get it now. Please correct me if I missing something. > > > Flags status hints, > > - DESC_DRIVER only: driver owns the descriptor w/o available info ready for device to use > > - DESC_DRIVER | DESC_WRAP: driver has prepared an available descriptor, device hasn't used it yet > > - None: device has used the descriptor, and write descriptor out > > - DESC_WRAP only: shall not happen, device make sure to clear it > > > Polling behavior is, > > - Device monitor DESC_...

...> > Get it now. Please correct me if I missing something. > > > > > > > > > Flags status hints, > > > > > > - DESC_DRIVER only: driver owns the descriptor w/o available info ready for device to use > > > > > > - DESC_DRIVER | DESC_WRAP: driver has prepared an available descriptor, device hasn't used it yet > > > > > > - None: device has used the descriptor, and write descriptor out > > > > > > - DESC_WRAP only: shall not happen, device make sure to clear it > > > > > >...

...t; of driver descriptors, and not all descriptors have to be written out. > > Driver and device are expected to maintain (internally) a wrap-around bit, > starting at 0 and changing value each time they start writing out descriptors > at the beginning of the ring. This bit is passed as DESC_WRAP bit in the flags > field. One simple question there, trying to understand the usage of DESC_WRAP flag. DESC_WRAP bit is a new flag since v2. It's used to address 'non power-of-2 ring sizes' mentioned in v2? Being confused by the statement of wrap-around bit here, it's an inter...

On 2017?09?10? 13:06, Michael S. Tsirkin wrote: > This is an update from v2 version. > Changes: > - update event suppression mechanism > - add wrap counter: DESC_WRAP flag in addition to > DESC_DRIVER flag used for validity so device does not have to > write out all used descriptors. Do we have benchmark result to show the advantage of DESC_DRIVER over e.g avail/used index? > - more options especially helpful for hardware implementations > -...

On Tue, Sep 26, 2017 at 11:38:18PM +0000, Steven Luong (sluong) wrote: > Michael, > > Would you please give an example or two how these two flags DESC_DRIVER and DESC_WRAP are used together? Like others, I am confused by the description and still don?t quite grok it. > > Steven My bad, I will need to work on it. Here is an example: Let's assume device promised to consume packets in order ring size = 2 Ring is 0 initialized. Device initially polls DESC...

This is an update from v1 version. Changes: - update event suppression mechanism - separate options for indirect and direct s/g - lots of new features --- Performance analysis of this is in my kvm forum 2016 presentation. The idea is to have a r/w descriptor in a ring structure, replacing the used and available ring, index and descriptor buffer. * Descriptor ring: Guest adds descriptors with

This is an update from v1 version. Changes: - update event suppression mechanism - separate options for indirect and direct s/g - lots of new features --- Performance analysis of this is in my kvm forum 2016 presentation. The idea is to have a r/w descriptor in a ring structure, replacing the used and available ring, index and descriptor buffer. * Descriptor ring: Guest adds descriptors with

On Mon, Sep 11, 2017 at 3:47 AM, Jason Wang <jasowang at redhat.com> wrote: > > > On 2017?09?10? 13:06, Michael S. Tsirkin wrote: >> >> This is an update from v2 version. >> Changes: >> - update event suppression mechanism >> - add wrap counter: DESC_WRAP flag in addition to >> DESC_DRIVER flag used for validity so device does not have to >> write out all used descriptors. > > > Do we have benchmark result to show the advantage of DESC_DRIVER over e.g > avail/used index? The KVM forum presentation has some numbers. I&...

On Mon, Sep 11, 2017 at 3:47 AM, Jason Wang <jasowang at redhat.com> wrote: > > > On 2017?09?10? 13:06, Michael S. Tsirkin wrote: >> >> This is an update from v2 version. >> Changes: >> - update event suppression mechanism >> - add wrap counter: DESC_WRAP flag in addition to >> DESC_DRIVER flag used for validity so device does not have to >> write out all used descriptors. > > > Do we have benchmark result to show the advantage of DESC_DRIVER over e.g > avail/used index? The KVM forum presentation has some numbers. I&...