| Message ID | ZeXQup48+X6U9TQ/@tpad (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next,-v3] net/core/dev.c: enable timestamp static key if CPU isolation is configured | expand |
Marcelo Tosatti wrote: > > For systems that use CPU isolation (via nohz_full), creating or destroying > a socket with - timestamping (SOCK_TIMESTAMPING_RX_SOFTWARE) might cause a + SO_TIMESTAMP, SO_TIMESTAMPNS or SO_TIMESTAMPING with flag + SOF_TIMESTAMPING_RX_SOFTWARE will cause a > static key to be enabled/disabled. This in turn causes undesired > IPIs to isolated CPUs. > > So enable the static key unconditionally, if CPU isolation is enabled, > thus avoiding the IPIs. > > Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> > diff --git a/net/core/dev.c b/net/core/dev.c > index c588808be77f..15a32f5900e6 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -155,6 +155,7 @@ > #include <net/netdev_rx_queue.h> > #include <net/page_pool/types.h> > #include <net/page_pool/helpers.h> > +#include <linux/sched/isolation.h> > > #include "dev.h" > #include "net-sysfs.h" > @@ -11851,3 +11852,14 @@ static int __init net_dev_init(void) > } > > subsys_initcall(net_dev_init); > + > +static int __init net_dev_late_init(void) > +{ > + /* avoid static key IPIs to isolated CPUs */ > + if (housekeeping_enabled(HK_TYPE_MISC)) > + net_enable_timestamp(); > + > + return 0; > +} > + > +late_initcall(net_dev_late_init); > Can this be included in the existing net_dev_init subsys_initcall? Aside from that small question LGTM.
Willem de Bruijn wrote: > Marcelo Tosatti wrote: > > > > For systems that use CPU isolation (via nohz_full), creating or destroying > > a socket with > > - timestamping (SOCK_TIMESTAMPING_RX_SOFTWARE) might cause a > + SO_TIMESTAMP, SO_TIMESTAMPNS or SO_TIMESTAMPING with flag > + SOF_TIMESTAMPING_RX_SOFTWARE will cause a > > > static key to be enabled/disabled. This in turn causes undesired > > IPIs to isolated CPUs. > > > > So enable the static key unconditionally, if CPU isolation is enabled, > > thus avoiding the IPIs. > > > > Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> > > > diff --git a/net/core/dev.c b/net/core/dev.c > > index c588808be77f..15a32f5900e6 100644 > > --- a/net/core/dev.c > > +++ b/net/core/dev.c > > @@ -155,6 +155,7 @@ > > #include <net/netdev_rx_queue.h> > > #include <net/page_pool/types.h> > > #include <net/page_pool/helpers.h> > > +#include <linux/sched/isolation.h> > > > > #include "dev.h" > > #include "net-sysfs.h" > > @@ -11851,3 +11852,14 @@ static int __init net_dev_init(void) > > } > > > > subsys_initcall(net_dev_init); > > + > > +static int __init net_dev_late_init(void) > > +{ > > + /* avoid static key IPIs to isolated CPUs */ > > + if (housekeeping_enabled(HK_TYPE_MISC)) > > + net_enable_timestamp(); > > + > > + return 0; > > +} > > + > > +late_initcall(net_dev_late_init); > > > > Can this be included in the existing net_dev_init > subsys_initcall? You sent a v4, but can you answer this question?
diff --git a/net/core/dev.c b/net/core/dev.c index c588808be77f..15a32f5900e6 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -155,6 +155,7 @@ #include <net/netdev_rx_queue.h> #include <net/page_pool/types.h> #include <net/page_pool/helpers.h> +#include <linux/sched/isolation.h> #include "dev.h" #include "net-sysfs.h" @@ -11851,3 +11852,14 @@ static int __init net_dev_init(void) } subsys_initcall(net_dev_init); + +static int __init net_dev_late_init(void) +{ + /* avoid static key IPIs to isolated CPUs */ + if (housekeeping_enabled(HK_TYPE_MISC)) + net_enable_timestamp(); + + return 0; +} + +late_initcall(net_dev_late_init);
For systems that use CPU isolation (via nohz_full), creating or destroying a socket with timestamping (SOCK_TIMESTAMPING_RX_SOFTWARE) might cause a static key to be enabled/disabled. This in turn causes undesired IPIs to isolated CPUs. So enable the static key unconditionally, if CPU isolation is enabled, thus avoiding the IPIs. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> --- v2: mention SOF_TIMESTAMPING_OPT_TX_SWHW in the commit log (Willem de Bruijn / Paolo Abeni) v3: SOF_TIMESTAMPING_OPT_TX_SWHW is irrelevant (Willem de Bruijn)