| Message ID | 1519723268-28723-1-git-send-email-junjie.j.chen@intel.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Delegated to: | Maxime Coquelin |
| Headers | show |
| Context | Check | Description |
|---|---|---|
| ci/checkpatch | success | coding style OK |
| ci/Intel-compilation | success | Compilation OK |
On 02/27/2018 10:21 AM, Junjie Chen wrote: > In vhost-switch example, when binding nic to vfio-pci, dequeue zero > copy cannot work in VM2NIC mode due to no iommu dma mapping is setup > for guest memory currently. > > Signed-off-by: Junjie Chen <junjie.j.chen@intel.com> > --- > Changes in V2: > - add doc in vhost lib > > doc/guides/prog_guide/vhost_lib.rst | 3 +++ > doc/guides/sample_app_ug/vhost.rst | 5 ++++- > 2 files changed, 7 insertions(+), 1 deletion(-) > > diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst > index 18227b6..bdf77d6 100644 > --- a/doc/guides/prog_guide/vhost_lib.rst > +++ b/doc/guides/prog_guide/vhost_lib.rst > @@ -83,6 +83,9 @@ The following is an overview of some key Vhost API functions: > of those segments, thus the fewer the segments, the quicker we will get > the mapping. NOTE: we may speed it by using tree searching in future. > > + * zero copy does not work when using vfio-pci driver currently, this is > + because we don't setup iommu dma mapping for guest memory. > + I guess that it should work with vfio-pci in noiommu mode? Maybe worth to clarify. > - ``RTE_VHOST_USER_IOMMU_SUPPORT`` > > IOMMU support will be enabled when this flag is set. It is disabled by > diff --git a/doc/guides/sample_app_ug/vhost.rst b/doc/guides/sample_app_ug/vhost.rst > index a4bdc6a..840c1fd 100644 > --- a/doc/guides/sample_app_ug/vhost.rst > +++ b/doc/guides/sample_app_ug/vhost.rst > @@ -147,7 +147,10 @@ retries on an RX burst, it takes effect only when rx retry is enabled. The > default value is 15. > > **--dequeue-zero-copy** > -Dequeue zero copy will be enabled when this option is given. > +Dequeue zero copy will be enabled when this option is given, it is worth to > +note that if NIC is binded to vfio-pci driver, dequeue zero copy cannot work > +at VM2NIC mode (vm2vm=0) due to currently we don't setup iommu dma mapping for > +guest memory. > > **--vlan-strip 0|1** > VLAN strip option is removed, because different NICs have different behaviors >
> -----Original Message----- > From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com] > Sent: Tuesday, March 6, 2018 4:57 PM > To: Chen, Junjie J <junjie.j.chen@intel.com>; yliu@fridaylinux.org; Tan, > Jianfeng <jianfeng.tan@intel.com> > Cc: dev@dpdk.org > Subject: Re: [PATCH v2] doc: add driver limitation for vhost dequeue zero copy > > > > On 02/27/2018 10:21 AM, Junjie Chen wrote: > > In vhost-switch example, when binding nic to vfio-pci, dequeue zero > > copy cannot work in VM2NIC mode due to no iommu dma mapping is setup > > for guest memory currently. > > > > Signed-off-by: Junjie Chen <junjie.j.chen@intel.com> > > --- > > Changes in V2: > > - add doc in vhost lib > > > > doc/guides/prog_guide/vhost_lib.rst | 3 +++ > > doc/guides/sample_app_ug/vhost.rst | 5 ++++- > > 2 files changed, 7 insertions(+), 1 deletion(-) > > > > diff --git a/doc/guides/prog_guide/vhost_lib.rst > > b/doc/guides/prog_guide/vhost_lib.rst > > index 18227b6..bdf77d6 100644 > > --- a/doc/guides/prog_guide/vhost_lib.rst > > +++ b/doc/guides/prog_guide/vhost_lib.rst > > @@ -83,6 +83,9 @@ The following is an overview of some key Vhost API > functions: > > of those segments, thus the fewer the segments, the quicker we > will get > > the mapping. NOTE: we may speed it by using tree searching in > future. > > > > + * zero copy does not work when using vfio-pci driver currently, this is > > + because we don't setup iommu dma mapping for guest memory. > > + > > I guess that it should work with vfio-pci in noiommu mode? Maybe worth to > clarify. You are right, it works on noiommu mode. Updated patch accordingly. > > > - ``RTE_VHOST_USER_IOMMU_SUPPORT`` > > > > IOMMU support will be enabled when this flag is set. It is > > disabled by diff --git a/doc/guides/sample_app_ug/vhost.rst > > b/doc/guides/sample_app_ug/vhost.rst > > index a4bdc6a..840c1fd 100644 > > --- a/doc/guides/sample_app_ug/vhost.rst > > +++ b/doc/guides/sample_app_ug/vhost.rst > > @@ -147,7 +147,10 @@ retries on an RX burst, it takes effect only when rx > retry is enabled. The > > default value is 15. > > > > **--dequeue-zero-copy** > > -Dequeue zero copy will be enabled when this option is given. > > +Dequeue zero copy will be enabled when this option is given, it is > > +worth to note that if NIC is binded to vfio-pci driver, dequeue zero > > +copy cannot work at VM2NIC mode (vm2vm=0) due to currently we don't > > +setup iommu dma mapping for guest memory. > > > > **--vlan-strip 0|1** > > VLAN strip option is removed, because different NICs have different > > behaviors > >
diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst index 18227b6..bdf77d6 100644 --- a/doc/guides/prog_guide/vhost_lib.rst +++ b/doc/guides/prog_guide/vhost_lib.rst @@ -83,6 +83,9 @@ The following is an overview of some key Vhost API functions: of those segments, thus the fewer the segments, the quicker we will get the mapping. NOTE: we may speed it by using tree searching in future. + * zero copy does not work when using vfio-pci driver currently, this is + because we don't setup iommu dma mapping for guest memory. + - ``RTE_VHOST_USER_IOMMU_SUPPORT`` IOMMU support will be enabled when this flag is set. It is disabled by diff --git a/doc/guides/sample_app_ug/vhost.rst b/doc/guides/sample_app_ug/vhost.rst index a4bdc6a..840c1fd 100644 --- a/doc/guides/sample_app_ug/vhost.rst +++ b/doc/guides/sample_app_ug/vhost.rst @@ -147,7 +147,10 @@ retries on an RX burst, it takes effect only when rx retry is enabled. The default value is 15. **--dequeue-zero-copy** -Dequeue zero copy will be enabled when this option is given. +Dequeue zero copy will be enabled when this option is given, it is worth to +note that if NIC is binded to vfio-pci driver, dequeue zero copy cannot work +at VM2NIC mode (vm2vm=0) due to currently we don't setup iommu dma mapping for +guest memory. **--vlan-strip 0|1** VLAN strip option is removed, because different NICs have different behaviors
In vhost-switch example, when binding nic to vfio-pci, dequeue zero copy cannot work in VM2NIC mode due to no iommu dma mapping is setup for guest memory currently. Signed-off-by: Junjie Chen <junjie.j.chen@intel.com> --- Changes in V2: - add doc in vhost lib doc/guides/prog_guide/vhost_lib.rst | 3 +++ doc/guides/sample_app_ug/vhost.rst | 5 ++++- 2 files changed, 7 insertions(+), 1 deletion(-)