| Message ID | ZdeSHbRa3rtHE+2E@tpad (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next] net/core/dev.c: enable timestamp static key if CPU isolation is configured | expand |
Hi, On Thu, 2024-02-22 at 15:27 -0300, Marcelo Tosatti wrote: > For systems that use CPU isolation (via nohz_full), creating or destroying > a socket with timestamping (SOF_TIMESTAMPING_OPT_TX_SWHW) might cause a > static key to be enabled/disabled. This in turn causes undesired > IPIs to isolated CPUs. I believe Willem is correct, the relevant flag is SOF_TIMESTAMPING_RX_SOFTWARE, see: https://elixir.bootlin.com/linux/v6.8-rc5/source/net/core/sock.c#L938 the example you used is a sort of API misuse, placing flag where a bool is expected. Please send a v2 with the updated commit message, you can mention both SO_TIMESTAMPING (SOF_TIMESTAMPING_RX_SOFTWARE) and SO_TIMESTAMP. Please also include Willem in recipients list, since he gave feedback on previous version. Thanks! Paolo
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 (SOF_TIMESTAMPING_OPT_TX_SWHW) 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>