| Message ID | 20240614064827.1299863-1-david.marchand@redhat.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [ovs-dev,v2] netdev-dpdk: Use LSC interrupt mode. | expand |
| Context | Check | Description |
|---|---|---|
| ovsrobot/apply-robot | success | apply and check: success |
| ovsrobot/github-robot-_Build_and_Test | success | github build: passed |
| ovsrobot/intel-ovs-compilation | success | test: success |
David Marchand, Jun 14, 2024 at 08:48: > Querying link status may get delayed for an undeterministic (long) time > with mlx5 ports. This is a consequence of the mlx5 driver calling ethtool > kernel API and getting stuck on the kernel RTNL lock while some other > operation is in progress under this lock. > > One impact for long link status query is that it is called under the bond > lock taken in write mode periodically in bond_run(). > In parallel, datapath threads may block requesting to read bonding related > info (like for example in bond_check_admissibility()). > > The LSC interrupt mode is available with many DPDK drivers and is used by > default with testpmd. > > It seems safe enough to switch on this feature by default in OVS. > We keep the per interface option to disable this feature in case of an > unforeseen bug. > > Signed-off-by: David Marchand <david.marchand@redhat.com> > --- > Changes since v1: > - (early) fail when interrupt lsc is requested by user but not supported > by the driver, > - otherwise, log a debug message if user did not request interrupt mode, This looks good to me. Is there a chance that this could be backported to the 3.1 branch? Reviewed-by: Robin Jarry <rjarry@redhat.com> Thanks David!
David Marchand, Jun 14, 2024 at 08:48: > diff --git a/NEWS b/NEWS > index 5ae0108d55..1e19beb793 100644 > --- a/NEWS > +++ b/NEWS > @@ -9,6 +9,9 @@ Post-v3.3.0 > https://github.com/openvswitch/ovs.git > - DPDK: > * OVS validated with DPDK 23.11.1. > + * Link status changes are now handled via interrupt mode if the DPDK > + driver supports it. It is possible to revert to polling mode by setting > + per interface 'dpdk-lsc-interrupt' other_config to 'false'. Nit pick: this setting is options:dpdk-lsc-interrupt not in other_config.
On Fri, Jun 14, 2024 at 2:48 AM David Marchand <david.marchand@redhat.com> wrote: > > Querying link status may get delayed for an undeterministic (long) time > with mlx5 ports. This is a consequence of the mlx5 driver calling ethtool > kernel API and getting stuck on the kernel RTNL lock while some other > operation is in progress under this lock. > > One impact for long link status query is that it is called under the bond > lock taken in write mode periodically in bond_run(). > In parallel, datapath threads may block requesting to read bonding related > info (like for example in bond_check_admissibility()). > > The LSC interrupt mode is available with many DPDK drivers and is used by > default with testpmd. > > It seems safe enough to switch on this feature by default in OVS. > We keep the per interface option to disable this feature in case of an > unforeseen bug. > > Signed-off-by: David Marchand <david.marchand@redhat.com> > --- > Changes since v1: > - (early) fail when interrupt lsc is requested by user but not supported > by the driver, > - otherwise, log a debug message if user did not request interrupt mode, > > --- > Documentation/topics/dpdk/phy.rst | 4 ++-- > NEWS | 3 +++ > lib/netdev-dpdk.c | 13 ++++++++++++- > vswitchd/vswitch.xml | 8 ++++---- > 4 files changed, 21 insertions(+), 7 deletions(-) > > diff --git a/Documentation/topics/dpdk/phy.rst b/Documentation/topics/dpdk/phy.rst > index efd168cba8..eefc25613d 100644 > --- a/Documentation/topics/dpdk/phy.rst > +++ b/Documentation/topics/dpdk/phy.rst > @@ -546,8 +546,8 @@ the firmware every time to fulfil this request. > > Note that not all PMD drivers support LSC interrupts. > > -The default configuration is polling mode. To set interrupt mode, option > -``dpdk-lsc-interrupt`` has to be set to ``true``. > +The default configuration is interrupt mode. To set polling mode, option > +``dpdk-lsc-interrupt`` has to be set to ``false``. > > Command to set interrupt mode for a specific interface:: > $ ovs-vsctl set interface <iface_name> options:dpdk-lsc-interrupt=true > diff --git a/NEWS b/NEWS > index 5ae0108d55..1e19beb793 100644 > --- a/NEWS > +++ b/NEWS > @@ -9,6 +9,9 @@ Post-v3.3.0 > https://github.com/openvswitch/ovs.git > - DPDK: > * OVS validated with DPDK 23.11.1. > + * Link status changes are now handled via interrupt mode if the DPDK > + driver supports it. It is possible to revert to polling mode by setting > + per interface 'dpdk-lsc-interrupt' other_config to 'false'. As Robin points out, other_config should be changed to options.But the rest looks good. Acked-by: Mike Pattrick <mkp@redhat.com> > > > v3.3.0 - 16 Feb 2024 > diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c > index 0fa37d5145..a260bc8485 100644 > --- a/lib/netdev-dpdk.c > +++ b/lib/netdev-dpdk.c > @@ -2397,7 +2397,18 @@ netdev_dpdk_set_config(struct netdev *netdev, const struct smap *args, > } > } > > - lsc_interrupt_mode = smap_get_bool(args, "dpdk-lsc-interrupt", false); > + lsc_interrupt_mode = smap_get_bool(args, "dpdk-lsc-interrupt", true); > + if (lsc_interrupt_mode && !(*info.dev_flags & RTE_ETH_DEV_INTR_LSC)) { > + if (smap_get(args, "dpdk-lsc-interrupt")) { > + VLOG_ERR("interface '%s': link status interrupt is not supported.", > + netdev_get_name(netdev)); > + err = EINVAL; > + goto out; > + } > + VLOG_DBG("interface '%s': not enabling link status interrupt.", > + netdev_get_name(netdev)); > + lsc_interrupt_mode = false; > + } > if (dev->requested_lsc_interrupt_mode != lsc_interrupt_mode) { > dev->requested_lsc_interrupt_mode = lsc_interrupt_mode; > netdev_request_reconfigure(netdev); > diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml > index 8a1b607d71..e3afb78a4e 100644 > --- a/vswitchd/vswitch.xml > +++ b/vswitchd/vswitch.xml > @@ -4647,12 +4647,12 @@ ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \ > <column name="options" key="dpdk-lsc-interrupt" > type='{"type": "boolean"}'> > <p> > - Set this value to <code>true</code> to configure interrupt mode for > - Link State Change (LSC) detection instead of poll mode for the DPDK > - interface. > + Set this value to <code>false</code> to configure poll mode for > + Link State Change (LSC) detection instead of interrupt mode for the > + DPDK interface. > </p> > <p> > - If this value is not set, poll mode is configured. > + If this value is not set, interrupt mode is configured. > </p> > <p> > This parameter has an effect only on netdev dpdk interfaces. > -- > 2.44.0 >
On Fri, Jun 14, 2024 at 10:40 AM Robin Jarry <rjarry@redhat.com> wrote: > > David Marchand, Jun 14, 2024 at 08:48: > > diff --git a/NEWS b/NEWS > > index 5ae0108d55..1e19beb793 100644 > > --- a/NEWS > > +++ b/NEWS > > @@ -9,6 +9,9 @@ Post-v3.3.0 > > https://github.com/openvswitch/ovs.git > > - DPDK: > > * OVS validated with DPDK 23.11.1. > > + * Link status changes are now handled via interrupt mode if the DPDK > > + driver supports it. It is possible to revert to polling mode by setting > > + per interface 'dpdk-lsc-interrupt' other_config to 'false'. > > Nit pick: this setting is options:dpdk-lsc-interrupt not in > other_config. > Oh, indeed.. fixed in v3. Thanks Robin.
On Fri, Jun 14, 2024 at 10:17 AM Robin Jarry <rjarry@redhat.com> wrote: > > David Marchand, Jun 14, 2024 at 08:48: > > Querying link status may get delayed for an undeterministic (long) time > > with mlx5 ports. This is a consequence of the mlx5 driver calling ethtool > > kernel API and getting stuck on the kernel RTNL lock while some other > > operation is in progress under this lock. > > > > One impact for long link status query is that it is called under the bond > > lock taken in write mode periodically in bond_run(). > > In parallel, datapath threads may block requesting to read bonding related > > info (like for example in bond_check_admissibility()). > > > > The LSC interrupt mode is available with many DPDK drivers and is used by > > default with testpmd. > > > > It seems safe enough to switch on this feature by default in OVS. > > We keep the per interface option to disable this feature in case of an > > unforeseen bug. > > > > Signed-off-by: David Marchand <david.marchand@redhat.com> > > --- > > Changes since v1: > > - (early) fail when interrupt lsc is requested by user but not supported > > by the driver, > > - otherwise, log a debug message if user did not request interrupt mode, > > This looks good to me. Is there a chance that this could be backported > to the 3.1 branch? Well, this changes a default behavior, so it may not be welcome in a stable branch. On the other hand, this helps resolving (not always trivial) random packet drops, so it is worth considering.
diff --git a/Documentation/topics/dpdk/phy.rst b/Documentation/topics/dpdk/phy.rst index efd168cba8..eefc25613d 100644 --- a/Documentation/topics/dpdk/phy.rst +++ b/Documentation/topics/dpdk/phy.rst @@ -546,8 +546,8 @@ the firmware every time to fulfil this request. Note that not all PMD drivers support LSC interrupts. -The default configuration is polling mode. To set interrupt mode, option -``dpdk-lsc-interrupt`` has to be set to ``true``. +The default configuration is interrupt mode. To set polling mode, option +``dpdk-lsc-interrupt`` has to be set to ``false``. Command to set interrupt mode for a specific interface:: $ ovs-vsctl set interface <iface_name> options:dpdk-lsc-interrupt=true diff --git a/NEWS b/NEWS index 5ae0108d55..1e19beb793 100644 --- a/NEWS +++ b/NEWS @@ -9,6 +9,9 @@ Post-v3.3.0 https://github.com/openvswitch/ovs.git - DPDK: * OVS validated with DPDK 23.11.1. + * Link status changes are now handled via interrupt mode if the DPDK + driver supports it. It is possible to revert to polling mode by setting + per interface 'dpdk-lsc-interrupt' other_config to 'false'. v3.3.0 - 16 Feb 2024 diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c index 0fa37d5145..a260bc8485 100644 --- a/lib/netdev-dpdk.c +++ b/lib/netdev-dpdk.c @@ -2397,7 +2397,18 @@ netdev_dpdk_set_config(struct netdev *netdev, const struct smap *args, } } - lsc_interrupt_mode = smap_get_bool(args, "dpdk-lsc-interrupt", false); + lsc_interrupt_mode = smap_get_bool(args, "dpdk-lsc-interrupt", true); + if (lsc_interrupt_mode && !(*info.dev_flags & RTE_ETH_DEV_INTR_LSC)) { + if (smap_get(args, "dpdk-lsc-interrupt")) { + VLOG_ERR("interface '%s': link status interrupt is not supported.", + netdev_get_name(netdev)); + err = EINVAL; + goto out; + } + VLOG_DBG("interface '%s': not enabling link status interrupt.", + netdev_get_name(netdev)); + lsc_interrupt_mode = false; + } if (dev->requested_lsc_interrupt_mode != lsc_interrupt_mode) { dev->requested_lsc_interrupt_mode = lsc_interrupt_mode; netdev_request_reconfigure(netdev); diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml index 8a1b607d71..e3afb78a4e 100644 --- a/vswitchd/vswitch.xml +++ b/vswitchd/vswitch.xml @@ -4647,12 +4647,12 @@ ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \ <column name="options" key="dpdk-lsc-interrupt" type='{"type": "boolean"}'> <p> - Set this value to <code>true</code> to configure interrupt mode for - Link State Change (LSC) detection instead of poll mode for the DPDK - interface. + Set this value to <code>false</code> to configure poll mode for + Link State Change (LSC) detection instead of interrupt mode for the + DPDK interface. </p> <p> - If this value is not set, poll mode is configured. + If this value is not set, interrupt mode is configured. </p> <p> This parameter has an effect only on netdev dpdk interfaces.
Querying link status may get delayed for an undeterministic (long) time with mlx5 ports. This is a consequence of the mlx5 driver calling ethtool kernel API and getting stuck on the kernel RTNL lock while some other operation is in progress under this lock. One impact for long link status query is that it is called under the bond lock taken in write mode periodically in bond_run(). In parallel, datapath threads may block requesting to read bonding related info (like for example in bond_check_admissibility()). The LSC interrupt mode is available with many DPDK drivers and is used by default with testpmd. It seems safe enough to switch on this feature by default in OVS. We keep the per interface option to disable this feature in case of an unforeseen bug. Signed-off-by: David Marchand <david.marchand@redhat.com> --- Changes since v1: - (early) fail when interrupt lsc is requested by user but not supported by the driver, - otherwise, log a debug message if user did not request interrupt mode, --- Documentation/topics/dpdk/phy.rst | 4 ++-- NEWS | 3 +++ lib/netdev-dpdk.c | 13 ++++++++++++- vswitchd/vswitch.xml | 8 ++++---- 4 files changed, 21 insertions(+), 7 deletions(-)