[v3,1/2] mbuf: add function returning default buffer address
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Commit Message
This patch introduces two new functions - rte_mbuf_buf_addr() and
rte_mbuf_data_addr_default().
rte_mbuf_buf_addr() reutrns the default buffer address of given mbuf which
comes after mbuf structure and private data.
rte_mbuf_data_addr_default() returns the default address of mbuf data
taking the headroom into account.
Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
---
v3:
* rename functions
v2:
* initial implementation
lib/librte_mbuf/rte_mbuf.h | 43 ++++++++++++++++++++++++++++++++++++++++---
1 file changed, 40 insertions(+), 3 deletions(-)
Comments
On 1/10/19 9:35 PM, Yongseok Koh wrote:
> This patch introduces two new functions - rte_mbuf_buf_addr() and
> rte_mbuf_data_addr_default().
>
> rte_mbuf_buf_addr() reutrns the default buffer address of given mbuf which
> comes after mbuf structure and private data.
>
> rte_mbuf_data_addr_default() returns the default address of mbuf data
> taking the headroom into account.
>
> Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> ---
>
> v3:
> * rename functions
>
> v2:
> * initial implementation
>
> lib/librte_mbuf/rte_mbuf.h | 43 ++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 40 insertions(+), 3 deletions(-)
>
> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> index bc562dc8a9..486566fc28 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -788,8 +788,47 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi)
> }
>
> /**
> + * Return the default buffer address of the mbuf.
> + *
> + * @param mb
> + * The pointer to the mbuf.
> + * @param mp
> + * The pointer to the mempool of the mbuf.
> + * @return
> + * The pointer of the mbuf buffer.
> + */
> +static inline char * __rte_experimental
> +rte_mbuf_buf_addr(struct rte_mbuf *mb, struct rte_mempool *mp)
struct rte_mbuf has pool member. So, I don't understand why mp
argument is required. I guess there is a reason, but it should be
explained in comments. I see motivation in rte_mbuf_to_baddr()
description, but rte_mbuf_buf_add() does not explain it.
Also right now the function name looks like simple get accessor for
buf_addr and I'd expect to seem one line implementation may be
with extra debug checks: return mb->buf_addr.
May be rte_mbuf_direct_buf_addr() ?
If so, similar below rte_mbuf_direct_data_addr_default().
> +{
> + char *buffer_addr;
> +
> + buffer_addr = (char *)mb + sizeof(*mb) + rte_pktmbuf_priv_size(mp);
> + return buffer_addr;
> +}
> +
> +
> +/**
> + * Return the default address of the beginning of the mbuf data.
> + *
> + * @param mb
> + * The pointer to the mbuf.
> + * @return
> + * The pointer of the beginning of the mbuf data.
> + */
> +static inline char * __rte_experimental
> +rte_mbuf_data_addr_default(struct rte_mbuf *mb)
> +{
> + return rte_mbuf_buf_addr(mb, mb->pool) + RTE_PKTMBUF_HEADROOM;
> +}
> +
> +/**
> * Return the buffer address embedded in the given mbuf.
> *
> + * Note that accessing mempool pointer of a mbuf is expensive because the
> + * pointer is stored in the 2nd cache line of mbuf. If mempool is known, it
> + * is better not to reference the mempool pointer in mbuf but calling
> + * rte_mbuf_buf_addr() would be more efficient.
> + *
> * @param md
> * The pointer to the mbuf.
> * @return
> @@ -798,9 +837,7 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi)
> static inline char *
> rte_mbuf_to_baddr(struct rte_mbuf *md)
> {
> - char *buffer_addr;
> - buffer_addr = (char *)md + sizeof(*md) + rte_pktmbuf_priv_size(md->pool);
> - return buffer_addr;
> + return rte_mbuf_buf_addr(md, md->pool);
> }
>
> /**
On Fri, Jan 11, 2019 at 11:14:22AM +0300, Andrew Rybchenko wrote:
> On 1/10/19 9:35 PM, Yongseok Koh wrote:
> > This patch introduces two new functions - rte_mbuf_buf_addr() and
> > rte_mbuf_data_addr_default().
> >
> > rte_mbuf_buf_addr() reutrns the default buffer address of given mbuf which
> > comes after mbuf structure and private data.
> >
> > rte_mbuf_data_addr_default() returns the default address of mbuf data
> > taking the headroom into account.
> >
> > Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> > ---
> >
> > v3:
> > * rename functions
> >
> > v2:
> > * initial implementation
> >
> > lib/librte_mbuf/rte_mbuf.h | 43 ++++++++++++++++++++++++++++++++++++++++---
> > 1 file changed, 40 insertions(+), 3 deletions(-)
> >
> > diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> > index bc562dc8a9..486566fc28 100644
> > --- a/lib/librte_mbuf/rte_mbuf.h
> > +++ b/lib/librte_mbuf/rte_mbuf.h
> > @@ -788,8 +788,47 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi)
> > }
> > /**
> > + * Return the default buffer address of the mbuf.
> > + *
> > + * @param mb
> > + * The pointer to the mbuf.
> > + * @param mp
> > + * The pointer to the mempool of the mbuf.
> > + * @return
> > + * The pointer of the mbuf buffer.
> > + */
> > +static inline char * __rte_experimental
> > +rte_mbuf_buf_addr(struct rte_mbuf *mb, struct rte_mempool *mp)
>
> struct rte_mbuf has pool member. So, I don't understand why mp
> argument is required. I guess there is a reason, but it should be
> explained in comments. I see motivation in rte_mbuf_to_baddr()
> description, but rte_mbuf_buf_add() does not explain it.
Well, I don't like to put same comment here and there but I'll add small comment
here.
> Also right now the function name looks like simple get accessor for
> buf_addr and I'd expect to seem one line implementation may be
> with extra debug checks: return mb->buf_addr.
This func is suggested by David and Olivier because same code is being repeated
in multiple locations. This can be used to initialize a mbuf when mb->buf_addr is
null. And second use-case (this is my use-case) is to get the buf_addr without
accessing the mbuf struct when mempool of mbuf is known, e.g. Rx buffer
replenishment. It is definitely beneficial for performance, especially RISC
cores.
> May be rte_mbuf_direct_buf_addr() ?
> If so, similar below rte_mbuf_direct_data_addr_default().
Regarding naming, people have different tastes. As it is acked by Olivier and
David, I'll keep the names.
Thanks,
Yongseok
> > +{
> > + char *buffer_addr;
> > +
> > + buffer_addr = (char *)mb + sizeof(*mb) + rte_pktmbuf_priv_size(mp);
> > + return buffer_addr;
> > +}
> > +
> > +
> > +/**
> > + * Return the default address of the beginning of the mbuf data.
> > + *
> > + * @param mb
> > + * The pointer to the mbuf.
> > + * @return
> > + * The pointer of the beginning of the mbuf data.
> > + */
> > +static inline char * __rte_experimental
> > +rte_mbuf_data_addr_default(struct rte_mbuf *mb)
> > +{
> > + return rte_mbuf_buf_addr(mb, mb->pool) + RTE_PKTMBUF_HEADROOM;
> > +}
> > +
> > +/**
> > * Return the buffer address embedded in the given mbuf.
> > *
> > + * Note that accessing mempool pointer of a mbuf is expensive because the
> > + * pointer is stored in the 2nd cache line of mbuf. If mempool is known, it
> > + * is better not to reference the mempool pointer in mbuf but calling
> > + * rte_mbuf_buf_addr() would be more efficient.
> > + *
> > * @param md
> > * The pointer to the mbuf.
> > * @return
> > @@ -798,9 +837,7 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi)
> > static inline char *
> > rte_mbuf_to_baddr(struct rte_mbuf *md)
> > {
> > - char *buffer_addr;
> > - buffer_addr = (char *)md + sizeof(*md) + rte_pktmbuf_priv_size(md->pool);
> > - return buffer_addr;
> > + return rte_mbuf_buf_addr(md, md->pool);
> > }
> > /**
>
Olivier, David,
could you take a look at naming suggested below and share your thoughts.
My fear is that rte_mbuf_buf_addr() is too generic and true for direct mbuf
only. That's why I'd like to highlight it in the function name.
Thanks,
Andrew.
On 1/11/19 2:03 PM, Yongseok Koh wrote:
> On Fri, Jan 11, 2019 at 11:14:22AM +0300, Andrew Rybchenko wrote:
>> On 1/10/19 9:35 PM, Yongseok Koh wrote:
>>> This patch introduces two new functions - rte_mbuf_buf_addr() and
>>> rte_mbuf_data_addr_default().
>>>
>>> rte_mbuf_buf_addr() reutrns the default buffer address of given mbuf which
>>> comes after mbuf structure and private data.
>>>
>>> rte_mbuf_data_addr_default() returns the default address of mbuf data
>>> taking the headroom into account.
>>>
>>> Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
>>> ---
>>>
>>> v3:
>>> * rename functions
>>>
>>> v2:
>>> * initial implementation
>>>
>>> lib/librte_mbuf/rte_mbuf.h | 43 ++++++++++++++++++++++++++++++++++++++++---
>>> 1 file changed, 40 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
>>> index bc562dc8a9..486566fc28 100644
>>> --- a/lib/librte_mbuf/rte_mbuf.h
>>> +++ b/lib/librte_mbuf/rte_mbuf.h
>>> @@ -788,8 +788,47 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi)
>>> }
>>> /**
>>> + * Return the default buffer address of the mbuf.
>>> + *
>>> + * @param mb
>>> + * The pointer to the mbuf.
>>> + * @param mp
>>> + * The pointer to the mempool of the mbuf.
>>> + * @return
>>> + * The pointer of the mbuf buffer.
>>> + */
>>> +static inline char * __rte_experimental
>>> +rte_mbuf_buf_addr(struct rte_mbuf *mb, struct rte_mempool *mp)
>> struct rte_mbuf has pool member. So, I don't understand why mp
>> argument is required. I guess there is a reason, but it should be
>> explained in comments. I see motivation in rte_mbuf_to_baddr()
>> description, but rte_mbuf_buf_add() does not explain it.
> Well, I don't like to put same comment here and there but I'll add small comment
> here.
>
>> Also right now the function name looks like simple get accessor for
>> buf_addr and I'd expect to seem one line implementation may be
>> with extra debug checks: return mb->buf_addr.
> This func is suggested by David and Olivier because same code is being repeated
> in multiple locations. This can be used to initialize a mbuf when mb->buf_addr is
> null. And second use-case (this is my use-case) is to get the buf_addr without
> accessing the mbuf struct when mempool of mbuf is known, e.g. Rx buffer
> replenishment. It is definitely beneficial for performance, especially RISC
> cores.
>
>> May be rte_mbuf_direct_buf_addr() ?
>> If so, similar below rte_mbuf_direct_data_addr_default().
> Regarding naming, people have different tastes. As it is acked by Olivier and
> David, I'll keep the names.
> Thanks,
> Yongseok
>
>>> +{
>>> + char *buffer_addr;
>>> +
>>> + buffer_addr = (char *)mb + sizeof(*mb) + rte_pktmbuf_priv_size(mp);
>>> + return buffer_addr;
>>> +}
>>> +
>>> +
>>> +/**
>>> + * Return the default address of the beginning of the mbuf data.
>>> + *
>>> + * @param mb
>>> + * The pointer to the mbuf.
>>> + * @return
>>> + * The pointer of the beginning of the mbuf data.
>>> + */
>>> +static inline char * __rte_experimental
>>> +rte_mbuf_data_addr_default(struct rte_mbuf *mb)
>>> +{
>>> + return rte_mbuf_buf_addr(mb, mb->pool) + RTE_PKTMBUF_HEADROOM;
>>> +}
>>> +
>>> +/**
>>> * Return the buffer address embedded in the given mbuf.
>>> *
>>> + * Note that accessing mempool pointer of a mbuf is expensive because the
>>> + * pointer is stored in the 2nd cache line of mbuf. If mempool is known, it
>>> + * is better not to reference the mempool pointer in mbuf but calling
>>> + * rte_mbuf_buf_addr() would be more efficient.
>>> + *
>>> * @param md
>>> * The pointer to the mbuf.
>>> * @return
>>> @@ -798,9 +837,7 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi)
>>> static inline char *
>>> rte_mbuf_to_baddr(struct rte_mbuf *md)
>>> {
>>> - char *buffer_addr;
>>> - buffer_addr = (char *)md + sizeof(*md) + rte_pktmbuf_priv_size(md->pool);
>>> - return buffer_addr;
>>> + return rte_mbuf_buf_addr(md, md->pool);
>>> }
>>> /**
> On Jan 11, 2019, at 3:17 AM, Andrew Rybchenko <arybchenko@solarflare.com> wrote:
>
> Olivier, David,
>
> could you take a look at naming suggested below and share your thoughts.
> My fear is that rte_mbuf_buf_addr() is too generic and true for direct mbuf
> only. That's why I'd like to highlight it in the function name.
Like the existing rte_mbuf_to_baddr(), it is to return the buf_addr of
the given mbuf. It doesn't matter whether the given mbuf is direct or not.
It should be used at user's discretion.
Yongseok
> On 1/11/19 2:03 PM, Yongseok Koh wrote:
>> On Fri, Jan 11, 2019 at 11:14:22AM +0300, Andrew Rybchenko wrote:
>>
>>> On 1/10/19 9:35 PM, Yongseok Koh wrote:
>>>
>>>> This patch introduces two new functions - rte_mbuf_buf_addr() and
>>>> rte_mbuf_data_addr_default().
>>>>
>>>> rte_mbuf_buf_addr() reutrns the default buffer address of given mbuf which
>>>> comes after mbuf structure and private data.
>>>>
>>>> rte_mbuf_data_addr_default() returns the default address of mbuf data
>>>> taking the headroom into account.
>>>>
>>>> Signed-off-by: Yongseok Koh
>>>> <yskoh@mellanox.com>
>>>>
>>>> ---
>>>>
>>>> v3:
>>>> * rename functions
>>>>
>>>> v2:
>>>> * initial implementation
>>>>
>>>> lib/librte_mbuf/rte_mbuf.h | 43 ++++++++++++++++++++++++++++++++++++++++---
>>>> 1 file changed, 40 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
>>>> index bc562dc8a9..486566fc28 100644
>>>> --- a/lib/librte_mbuf/rte_mbuf.h
>>>> +++ b/lib/librte_mbuf/rte_mbuf.h
>>>> @@ -788,8 +788,47 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi)
>>>> }
>>>> /**
>>>> + * Return the default buffer address of the mbuf.
>>>> + *
>>>> + * @param mb
>>>> + * The pointer to the mbuf.
>>>> + * @param mp
>>>> + * The pointer to the mempool of the mbuf.
>>>> + * @return
>>>> + * The pointer of the mbuf buffer.
>>>> + */
>>>> +static inline char * __rte_experimental
>>>> +rte_mbuf_buf_addr(struct rte_mbuf *mb, struct rte_mempool *mp)
>>>>
>>> struct rte_mbuf has pool member. So, I don't understand why mp
>>> argument is required. I guess there is a reason, but it should be
>>> explained in comments. I see motivation in rte_mbuf_to_baddr()
>>> description, but rte_mbuf_buf_add() does not explain it.
>>>
>> Well, I don't like to put same comment here and there but I'll add small comment
>> here.
>>
>>
>>> Also right now the function name looks like simple get accessor for
>>> buf_addr and I'd expect to seem one line implementation may be
>>> with extra debug checks: return mb->buf_addr.
>>>
>> This func is suggested by David and Olivier because same code is being repeated
>> in multiple locations. This can be used to initialize a mbuf when mb->buf_addr is
>> null. And second use-case (this is my use-case) is to get the buf_addr without
>> accessing the mbuf struct when mempool of mbuf is known, e.g. Rx buffer
>> replenishment. It is definitely beneficial for performance, especially RISC
>> cores.
>>
>>
>>> May be rte_mbuf_direct_buf_addr() ?
>>> If so, similar below rte_mbuf_direct_data_addr_default().
>>>
>> Regarding naming, people have different tastes. As it is acked by Olivier and
>> David, I'll keep the names.
>>
>
>> Thanks,
>> Yongseok
>>
>>
>>>> +{
>>>> + char *buffer_addr;
>>>> +
>>>> + buffer_addr = (char *)mb + sizeof(*mb) + rte_pktmbuf_priv_size(mp);
>>>> + return buffer_addr;
>>>> +}
>>>> +
>>>> +
>>>> +/**
>>>> + * Return the default address of the beginning of the mbuf data.
>>>> + *
>>>> + * @param mb
>>>> + * The pointer to the mbuf.
>>>> + * @return
>>>> + * The pointer of the beginning of the mbuf data.
>>>> + */
>>>> +static inline char * __rte_experimental
>>>> +rte_mbuf_data_addr_default(struct rte_mbuf *mb)
>>>> +{
>>>> + return rte_mbuf_buf_addr(mb, mb->pool) + RTE_PKTMBUF_HEADROOM;
>>>> +}
>>>> +
>>>> +/**
>>>> * Return the buffer address embedded in the given mbuf.
>>>> *
>>>> + * Note that accessing mempool pointer of a mbuf is expensive because the
>>>> + * pointer is stored in the 2nd cache line of mbuf. If mempool is known, it
>>>> + * is better not to reference the mempool pointer in mbuf but calling
>>>> + * rte_mbuf_buf_addr() would be more efficient.
>>>> + *
>>>> * @param md
>>>> * The pointer to the mbuf.
>>>> * @return
>>>> @@ -798,9 +837,7 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi)
>>>> static inline char *
>>>> rte_mbuf_to_baddr(struct rte_mbuf *md)
>>>> {
>>>> - char *buffer_addr;
>>>> - buffer_addr = (char *)md + sizeof(*md) + rte_pktmbuf_priv_size(md->pool);
>>>> - return buffer_addr;
>>>> + return rte_mbuf_buf_addr(md, md->pool);
>>>> }
>>>> /**
>>>>
>
On Fri, Jan 11, 2019 at 02:17:04PM +0300, Andrew Rybchenko wrote:
> Olivier, David,
>
> could you take a look at naming suggested below and share your thoughts.
> My fear is that rte_mbuf_buf_addr() is too generic and true for direct mbuf
> only. That's why I'd like to highlight it in the function name.
>
I would tend to agree with that concern.
/Bruce
> Thanks,
> Andrew.
>
> On 1/11/19 2:03 PM, Yongseok Koh wrote:
> > On Fri, Jan 11, 2019 at 11:14:22AM +0300, Andrew Rybchenko wrote:
> > > On 1/10/19 9:35 PM, Yongseok Koh wrote:
> > > > This patch introduces two new functions - rte_mbuf_buf_addr() and
> > > > rte_mbuf_data_addr_default().
> > > >
> > > > rte_mbuf_buf_addr() reutrns the default buffer address of given mbuf which
> > > > comes after mbuf structure and private data.
> > > >
> > > > rte_mbuf_data_addr_default() returns the default address of mbuf data
> > > > taking the headroom into account.
> > > >
> > > > Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> > > > ---
> > > >
> > > > v3:
> > > > * rename functions
> > > >
> > > > v2:
> > > > * initial implementation
> > > >
> > > > lib/librte_mbuf/rte_mbuf.h | 43 ++++++++++++++++++++++++++++++++++++++++---
> > > > 1 file changed, 40 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> > > > index bc562dc8a9..486566fc28 100644
> > > > --- a/lib/librte_mbuf/rte_mbuf.h
> > > > +++ b/lib/librte_mbuf/rte_mbuf.h
> > > > @@ -788,8 +788,47 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi)
> > > > }
> > > > /**
> > > > + * Return the default buffer address of the mbuf.
> > > > + *
> > > > + * @param mb
> > > > + * The pointer to the mbuf.
> > > > + * @param mp
> > > > + * The pointer to the mempool of the mbuf.
> > > > + * @return
> > > > + * The pointer of the mbuf buffer.
> > > > + */
> > > > +static inline char * __rte_experimental
> > > > +rte_mbuf_buf_addr(struct rte_mbuf *mb, struct rte_mempool *mp)
> > > struct rte_mbuf has pool member. So, I don't understand why mp
> > > argument is required. I guess there is a reason, but it should be
> > > explained in comments. I see motivation in rte_mbuf_to_baddr()
> > > description, but rte_mbuf_buf_add() does not explain it.
> > Well, I don't like to put same comment here and there but I'll add small comment
> > here.
> >
> > > Also right now the function name looks like simple get accessor for
> > > buf_addr and I'd expect to seem one line implementation may be
> > > with extra debug checks: return mb->buf_addr.
> > This func is suggested by David and Olivier because same code is being repeated
> > in multiple locations. This can be used to initialize a mbuf when mb->buf_addr is
> > null. And second use-case (this is my use-case) is to get the buf_addr without
> > accessing the mbuf struct when mempool of mbuf is known, e.g. Rx buffer
> > replenishment. It is definitely beneficial for performance, especially RISC
> > cores.
> >
> > > May be rte_mbuf_direct_buf_addr() ?
> > > If so, similar below rte_mbuf_direct_data_addr_default().
> > Regarding naming, people have different tastes. As it is acked by Olivier and
> > David, I'll keep the names.
>
> > Thanks,
> > Yongseok
> >
> > > > +{
> > > > + char *buffer_addr;
> > > > +
> > > > + buffer_addr = (char *)mb + sizeof(*mb) + rte_pktmbuf_priv_size(mp);
> > > > + return buffer_addr;
> > > > +}
> > > > +
> > > > +
> > > > +/**
> > > > + * Return the default address of the beginning of the mbuf data.
> > > > + *
> > > > + * @param mb
> > > > + * The pointer to the mbuf.
> > > > + * @return
> > > > + * The pointer of the beginning of the mbuf data.
> > > > + */
> > > > +static inline char * __rte_experimental
> > > > +rte_mbuf_data_addr_default(struct rte_mbuf *mb)
> > > > +{
> > > > + return rte_mbuf_buf_addr(mb, mb->pool) + RTE_PKTMBUF_HEADROOM;
> > > > +}
> > > > +
> > > > +/**
> > > > * Return the buffer address embedded in the given mbuf.
> > > > *
> > > > + * Note that accessing mempool pointer of a mbuf is expensive because the
> > > > + * pointer is stored in the 2nd cache line of mbuf. If mempool is known, it
> > > > + * is better not to reference the mempool pointer in mbuf but calling
> > > > + * rte_mbuf_buf_addr() would be more efficient.
> > > > + *
> > > > * @param md
> > > > * The pointer to the mbuf.
> > > > * @return
> > > > @@ -798,9 +837,7 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi)
> > > > static inline char *
> > > > rte_mbuf_to_baddr(struct rte_mbuf *md)
> > > > {
> > > > - char *buffer_addr;
> > > > - buffer_addr = (char *)md + sizeof(*md) + rte_pktmbuf_priv_size(md->pool);
> > > > - return buffer_addr;
> > > > + return rte_mbuf_buf_addr(md, md->pool);
> > > > }
> > > > /**
>
On Fri, Jan 11, 2019 at 12:57 PM Bruce Richardson <
bruce.richardson@intel.com> wrote:
> On Fri, Jan 11, 2019 at 02:17:04PM +0300, Andrew Rybchenko wrote:
> > Olivier, David,
> >
> > could you take a look at naming suggested below and share your thoughts.
> > My fear is that rte_mbuf_buf_addr() is too generic and true for direct
> mbuf
> > only. That's why I'd like to highlight it in the function name.
> >
>
> I would tend to agree with that concern.
>
I understand your concern as well.
The only usecase we have so far is for drivers on the rx side, so
implicitely direct mbufs.
But from a api user pov, explicit is always better.
I will let Olivier have the last word :-)
Hi,
On Fri, Jan 11, 2019 at 01:48:12PM +0100, David Marchand wrote:
> On Fri, Jan 11, 2019 at 12:57 PM Bruce Richardson <
> bruce.richardson@intel.com> wrote:
>
> > On Fri, Jan 11, 2019 at 02:17:04PM +0300, Andrew Rybchenko wrote:
> > > Olivier, David,
> > >
> > > could you take a look at naming suggested below and share your thoughts.
> > > My fear is that rte_mbuf_buf_addr() is too generic and true for direct
> > mbuf
> > > only. That's why I'd like to highlight it in the function name.
> > >
> >
> > I would tend to agree with that concern.
> >
>
> I understand your concern as well.
>
> The only usecase we have so far is for drivers on the rx side, so
> implicitely direct mbufs.
> But from a api user pov, explicit is always better.
>
> I will let Olivier have the last word :-)
Thanks Andrew for pointing this out.
However I agree with Yongseok: we already have many functions that
applies to direct mbufs that don't have "direct" in their names.
In my opinion, rte_mbuf_buf_addr() is a good name, but I think the
doxygen comment could be improved a bit to state that it returns the
pointer to the embedded data. I also think that a small comment
explaining why the mp arg is required would be helpful.
Thanks,
Olivier
@@ -788,8 +788,47 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi)
}
/**
+ * Return the default buffer address of the mbuf.
+ *
+ * @param mb
+ * The pointer to the mbuf.
+ * @param mp
+ * The pointer to the mempool of the mbuf.
+ * @return
+ * The pointer of the mbuf buffer.
+ */
+static inline char * __rte_experimental
+rte_mbuf_buf_addr(struct rte_mbuf *mb, struct rte_mempool *mp)
+{
+ char *buffer_addr;
+
+ buffer_addr = (char *)mb + sizeof(*mb) + rte_pktmbuf_priv_size(mp);
+ return buffer_addr;
+}
+
+
+/**
+ * Return the default address of the beginning of the mbuf data.
+ *
+ * @param mb
+ * The pointer to the mbuf.
+ * @return
+ * The pointer of the beginning of the mbuf data.
+ */
+static inline char * __rte_experimental
+rte_mbuf_data_addr_default(struct rte_mbuf *mb)
+{
+ return rte_mbuf_buf_addr(mb, mb->pool) + RTE_PKTMBUF_HEADROOM;
+}
+
+/**
* Return the buffer address embedded in the given mbuf.
*
+ * Note that accessing mempool pointer of a mbuf is expensive because the
+ * pointer is stored in the 2nd cache line of mbuf. If mempool is known, it
+ * is better not to reference the mempool pointer in mbuf but calling
+ * rte_mbuf_buf_addr() would be more efficient.
+ *
* @param md
* The pointer to the mbuf.
* @return
@@ -798,9 +837,7 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi)
static inline char *
rte_mbuf_to_baddr(struct rte_mbuf *md)
{
- char *buffer_addr;
- buffer_addr = (char *)md + sizeof(*md) + rte_pktmbuf_priv_size(md->pool);
- return buffer_addr;
+ return rte_mbuf_buf_addr(md, md->pool);
}
/**