[1/1] eal/linux: do not create user mem map repeatedly when it exists
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Commit Message
From: Yunjian Wang <wangyunjian@huawei.com>
Currently, we will create new user mem map entry for the same memory
segment, but in fact it has already been added to the user mem maps.
It's not necessary to create it twice.
Fixes: 0cbce3a167f1 ("vfio: skip DMA map failure if already mapped")
Cc: stable@dpdk.org
Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
---
lib/librte_eal/linux/eal_vfio.c | 7 +++++++
1 file changed, 7 insertions(+)
Comments
On 16-Jul-20 2:38 PM, wangyunjian wrote:
> From: Yunjian Wang <wangyunjian@huawei.com>
>
> Currently, we will create new user mem map entry for the same memory
> segment, but in fact it has already been added to the user mem maps.
> It's not necessary to create it twice.
>
> Fixes: 0cbce3a167f1 ("vfio: skip DMA map failure if already mapped")
> Cc: stable@dpdk.org
>
> Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
> ---
> lib/librte_eal/linux/eal_vfio.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/lib/librte_eal/linux/eal_vfio.c b/lib/librte_eal/linux/eal_vfio.c
> index abb12a354..d8a8c39ab 100644
> --- a/lib/librte_eal/linux/eal_vfio.c
> +++ b/lib/librte_eal/linux/eal_vfio.c
> @@ -1828,6 +1828,13 @@ container_dma_map(struct vfio_config *vfio_cfg, uint64_t vaddr, uint64_t iova,
> ret = -1;
> goto out;
> }
> +
> + /* we don't need create new user mem map entry
> + * for the same memory segment.
> + */
> + if (errno == EBUSY || errno == EEXIST)
> + goto out;
> +
I'm not sure i understand this patch. If we get errno, the call has
failed, which means we're doing "goto out" from a few lines above. Am i
missing something here?
> /* create new user mem map entry */
> new_map = &user_mem_maps->maps[user_mem_maps->n_maps++];
> new_map->addr = vaddr;
>
On 17-Jul-20 3:19 PM, Burakov, Anatoly wrote:
> On 16-Jul-20 2:38 PM, wangyunjian wrote:
>> From: Yunjian Wang <wangyunjian@huawei.com>
>>
>> Currently, we will create new user mem map entry for the same memory
>> segment, but in fact it has already been added to the user mem maps.
>> It's not necessary to create it twice.
>>
>> Fixes: 0cbce3a167f1 ("vfio: skip DMA map failure if already mapped")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
>> ---
>> lib/librte_eal/linux/eal_vfio.c | 7 +++++++
>> 1 file changed, 7 insertions(+)
>>
>> diff --git a/lib/librte_eal/linux/eal_vfio.c
>> b/lib/librte_eal/linux/eal_vfio.c
>> index abb12a354..d8a8c39ab 100644
>> --- a/lib/librte_eal/linux/eal_vfio.c
>> +++ b/lib/librte_eal/linux/eal_vfio.c
>> @@ -1828,6 +1828,13 @@ container_dma_map(struct vfio_config *vfio_cfg,
>> uint64_t vaddr, uint64_t iova,
>> ret = -1;
>> goto out;
>> }
>> +
>> + /* we don't need create new user mem map entry
>> + * for the same memory segment.
>> + */
>> + if (errno == EBUSY || errno == EEXIST)
>> + goto out;
>> +
>
> I'm not sure i understand this patch. If we get errno, the call has
> failed, which means we're doing "goto out" from a few lines above. Am i
> missing something here?
>
>> /* create new user mem map entry */
>> new_map = &user_mem_maps->maps[user_mem_maps->n_maps++];
>> new_map->addr = vaddr;
>>
>
>
Oh, i see, the actual functions will set errno and return 0.
I don't think it's an actual issue as compacting will presumably remove
the extra user mem map anyway. What exactly is being fixed here? Does
compacting user mem maps not remove the extra entry?
> -----Original Message-----
> From: Burakov, Anatoly [mailto:anatoly.burakov@intel.com]
> Sent: Friday, July 17, 2020 10:24 PM
> To: wangyunjian <wangyunjian@huawei.com>; dev@dpdk.org;
> david.marchand@redhat.com
> Cc: Lilijun (Jerry) <jerry.lilijun@huawei.com>; xudingke
> <xudingke@huawei.com>; stable@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 1/1] eal/linux: do not create user mem map
> repeatedly when it exists
>
> On 17-Jul-20 3:19 PM, Burakov, Anatoly wrote:
> > On 16-Jul-20 2:38 PM, wangyunjian wrote:
> >> From: Yunjian Wang <wangyunjian@huawei.com>
> >>
> >> Currently, we will create new user mem map entry for the same memory
> >> segment, but in fact it has already been added to the user mem maps.
> >> It's not necessary to create it twice.
> >>
> >> Fixes: 0cbce3a167f1 ("vfio: skip DMA map failure if already mapped")
> >> Cc: stable@dpdk.org
> >>
> >> Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
> >> ---
> >> lib/librte_eal/linux/eal_vfio.c | 7 +++++++
> >> 1 file changed, 7 insertions(+)
> >>
> >> diff --git a/lib/librte_eal/linux/eal_vfio.c
> >> b/lib/librte_eal/linux/eal_vfio.c index abb12a354..d8a8c39ab 100644
> >> --- a/lib/librte_eal/linux/eal_vfio.c
> >> +++ b/lib/librte_eal/linux/eal_vfio.c
> >> @@ -1828,6 +1828,13 @@ container_dma_map(struct vfio_config
> >> *vfio_cfg, uint64_t vaddr, uint64_t iova,
> >> ret = -1;
> >> goto out;
> >> }
> >> +
> >> + /* we don't need create new user mem map entry
> >> + * for the same memory segment.
> >> + */
> >> + if (errno == EBUSY || errno == EEXIST)
> >> + goto out;
> >> +
> >
> > I'm not sure i understand this patch. If we get errno, the call has
> > failed, which means we're doing "goto out" from a few lines above. Am
> > i missing something here?
> >
> >> /* create new user mem map entry */
> >> new_map =
> &user_mem_maps->maps[user_mem_maps->n_maps++];
> >> new_map->addr = vaddr;
> >>
> >
> >
>
> Oh, i see, the actual functions will set errno and return 0.
>
> I don't think it's an actual issue as compacting will presumably remove the
> extra user mem map anyway. What exactly is being fixed here? Does
> compacting user mem maps not remove the extra entry?
I read the codes about compacting user mem maps. Currently, the function
only merges adjacent user mem maps and does not remove the same entry.
How about removing the same entry in the fuction?
Thanks
Yunjian
>
> --
> Thanks,
> Anatoly
On 20-Jul-20 3:00 AM, wangyunjian wrote:
>> -----Original Message-----
>> From: Burakov, Anatoly [mailto:anatoly.burakov@intel.com]
>> Sent: Friday, July 17, 2020 10:24 PM
>> To: wangyunjian <wangyunjian@huawei.com>; dev@dpdk.org;
>> david.marchand@redhat.com
>> Cc: Lilijun (Jerry) <jerry.lilijun@huawei.com>; xudingke
>> <xudingke@huawei.com>; stable@dpdk.org
>> Subject: Re: [dpdk-dev] [PATCH 1/1] eal/linux: do not create user mem map
>> repeatedly when it exists
>>
>> On 17-Jul-20 3:19 PM, Burakov, Anatoly wrote:
>>> On 16-Jul-20 2:38 PM, wangyunjian wrote:
>>>> From: Yunjian Wang <wangyunjian@huawei.com>
>>>>
>>>> Currently, we will create new user mem map entry for the same memory
>>>> segment, but in fact it has already been added to the user mem maps.
>>>> It's not necessary to create it twice.
>>>>
>>>> Fixes: 0cbce3a167f1 ("vfio: skip DMA map failure if already mapped")
>>>> Cc: stable@dpdk.org
>>>>
>>>> Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
>>>> ---
>>>> lib/librte_eal/linux/eal_vfio.c | 7 +++++++
>>>> 1 file changed, 7 insertions(+)
>>>>
>>>> diff --git a/lib/librte_eal/linux/eal_vfio.c
>>>> b/lib/librte_eal/linux/eal_vfio.c index abb12a354..d8a8c39ab 100644
>>>> --- a/lib/librte_eal/linux/eal_vfio.c
>>>> +++ b/lib/librte_eal/linux/eal_vfio.c
>>>> @@ -1828,6 +1828,13 @@ container_dma_map(struct vfio_config
>>>> *vfio_cfg, uint64_t vaddr, uint64_t iova,
>>>> ret = -1;
>>>> goto out;
>>>> }
>>>> +
>>>> + /* we don't need create new user mem map entry
>>>> + * for the same memory segment.
>>>> + */
>>>> + if (errno == EBUSY || errno == EEXIST)
>>>> + goto out;
>>>> +
>>>
>>> I'm not sure i understand this patch. If we get errno, the call has
>>> failed, which means we're doing "goto out" from a few lines above. Am
>>> i missing something here?
>>>
>>>> /* create new user mem map entry */
>>>> new_map =
>> &user_mem_maps->maps[user_mem_maps->n_maps++];
>>>> new_map->addr = vaddr;
>>>>
>>>
>>>
>>
>> Oh, i see, the actual functions will set errno and return 0.
>>
>> I don't think it's an actual issue as compacting will presumably remove the
>> extra user mem map anyway. What exactly is being fixed here? Does
>> compacting user mem maps not remove the extra entry?
>
> I read the codes about compacting user mem maps. Currently, the function
> only merges adjacent user mem maps and does not remove the same entry.
>
> How about removing the same entry in the fuction?
I would've expected "the same" to be within the definition of
"adjacent". Can you confirm that this actually doesn't happen? If so,
then yes, probably compacting should do that, instead of relying on an
artifact of implementation.
>
> Thanks
> Yunjian
>
>>
>> --
>> Thanks,
>> Anatoly
> -----Original Message-----
> From: Burakov, Anatoly [mailto:anatoly.burakov@intel.com]
> Sent: Monday, July 20, 2020 7:46 PM
> To: wangyunjian <wangyunjian@huawei.com>; dev@dpdk.org;
> david.marchand@redhat.com
> Cc: Lilijun (Jerry) <jerry.lilijun@huawei.com>; xudingke
> <xudingke@huawei.com>; stable@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 1/1] eal/linux: do not create user mem map
> repeatedly when it exists
>
> On 20-Jul-20 3:00 AM, wangyunjian wrote:
> >> -----Original Message-----
> >> From: Burakov, Anatoly [mailto:anatoly.burakov@intel.com]
> >> Sent: Friday, July 17, 2020 10:24 PM
> >> To: wangyunjian <wangyunjian@huawei.com>; dev@dpdk.org;
> >> david.marchand@redhat.com
> >> Cc: Lilijun (Jerry) <jerry.lilijun@huawei.com>; xudingke
> >> <xudingke@huawei.com>; stable@dpdk.org
> >> Subject: Re: [dpdk-dev] [PATCH 1/1] eal/linux: do not create user mem
> >> map repeatedly when it exists
> >>
> >> On 17-Jul-20 3:19 PM, Burakov, Anatoly wrote:
> >>> On 16-Jul-20 2:38 PM, wangyunjian wrote:
> >>>> From: Yunjian Wang <wangyunjian@huawei.com>
> >>>>
> >>>> Currently, we will create new user mem map entry for the same
> >>>> memory segment, but in fact it has already been added to the user mem
> maps.
> >>>> It's not necessary to create it twice.
> >>>>
> >>>> Fixes: 0cbce3a167f1 ("vfio: skip DMA map failure if already
> >>>> mapped")
> >>>> Cc: stable@dpdk.org
> >>>>
> >>>> Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
> >>>> ---
> >>>> lib/librte_eal/linux/eal_vfio.c | 7 +++++++
> >>>> 1 file changed, 7 insertions(+)
> >>>>
> >>>> diff --git a/lib/librte_eal/linux/eal_vfio.c
> >>>> b/lib/librte_eal/linux/eal_vfio.c index abb12a354..d8a8c39ab 100644
> >>>> --- a/lib/librte_eal/linux/eal_vfio.c
> >>>> +++ b/lib/librte_eal/linux/eal_vfio.c
> >>>> @@ -1828,6 +1828,13 @@ container_dma_map(struct vfio_config
> >>>> *vfio_cfg, uint64_t vaddr, uint64_t iova,
> >>>> ret = -1;
> >>>> goto out;
> >>>> }
> >>>> +
> >>>> + /* we don't need create new user mem map entry
> >>>> + * for the same memory segment.
> >>>> + */
> >>>> + if (errno == EBUSY || errno == EEXIST)
> >>>> + goto out;
> >>>> +
> >>>
> >>> I'm not sure i understand this patch. If we get errno, the call has
> >>> failed, which means we're doing "goto out" from a few lines above.
> >>> Am i missing something here?
> >>>
> >>>> /* create new user mem map entry */
> >>>> new_map =
> >> &user_mem_maps->maps[user_mem_maps->n_maps++];
> >>>> new_map->addr = vaddr;
> >>>>
> >>>
> >>>
> >>
> >> Oh, i see, the actual functions will set errno and return 0.
> >>
> >> I don't think it's an actual issue as compacting will presumably
> >> remove the extra user mem map anyway. What exactly is being fixed
> >> here? Does compacting user mem maps not remove the extra entry?
> >
> > I read the codes about compacting user mem maps. Currently, the
> > function only merges adjacent user mem maps and does not remove the
> same entry.
> >
> > How about removing the same entry in the fuction?
>
> I would've expected "the same" to be within the definition of "adjacent". Can
> you confirm that this actually doesn't happen? If so, then yes, probably
> compacting should do that, instead of relying on an artifact of implementation.
OK, I will do that, will send the v2 later.
Thanks
Yunjian
>
> >
> > Thanks
> > Yunjian
> >
> >>
> >> --
> >> Thanks,
> >> Anatoly
>
>
> --
> Thanks,
> Anatoly
@@ -1828,6 +1828,13 @@ container_dma_map(struct vfio_config *vfio_cfg, uint64_t vaddr, uint64_t iova,
ret = -1;
goto out;
}
+
+ /* we don't need create new user mem map entry
+ * for the same memory segment.
+ */
+ if (errno == EBUSY || errno == EEXIST)
+ goto out;
+
/* create new user mem map entry */
new_map = &user_mem_maps->maps[user_mem_maps->n_maps++];
new_map->addr = vaddr;