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[35.194.87.55]) by smtp.gmail.com with ESMTPSA id k26-20020ac8605a000000b0042efc6ad5a9sm1740625qtm.23.2024.03.06.00.50.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Mar 2024 00:50:27 -0800 (PST) Date: Wed, 06 Mar 2024 03:50:27 -0500 From: Willem de Bruijn To: Marcelo Tosatti , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Willem de Bruijn , Jakub Kicinski , Eric Dumazet , Frederic Weisbecker , Valentin Schneider , Paolo Abeni Message-ID: <65e82e533857c_a463929462@willemb.c.googlers.com.notmuch> In-Reply-To: References: Subject: Re: [PATCH net-next -v3] net/core/dev.c: enable timestamp static key if CPU isolation is configured Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit 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 > 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 > #include > #include > +#include > > #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.