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[89.32.171.123]) by smtp.gmail.com with ESMTPSA id w12-20020a056402268c00b0049e65e4ff20sm984227edd.14.2023.02.03.03.23.49 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 03 Feb 2023 03:23:49 -0800 (PST) From: Eelco Chaudron To: Eddy Tao Cc: netdev@vger.kernel.org, Pravin B Shelar , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , dev@openvswitch.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next v6 1/1] net:openvswitch:reduce cpu_used_mask memory Date: Fri, 03 Feb 2023 12:23:49 +0100 X-Mailer: MailMate (1.14r5939) Message-ID: In-Reply-To: References: <20230203095118.276261-1-taoyuan_eddy@hotmail.com> MIME-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3 Feb 2023, at 10:51, Eddy Tao wrote: > Use actual CPU number instead of hardcoded value to decide the size > of 'cpu_used_mask' in 'struct sw_flow'. Below is the reason. > > 'struct cpumask cpu_used_mask' is embedded in struct sw_flow. > Its size is hardcoded to CONFIG_NR_CPUS bits, which can be > 8192 by default, it costs memory and slows down ovs_flow_alloc > > To address this, redefine cpu_used_mask to pointer > append cpumask_size() bytes after 'stat' to hold cpumask > > cpumask APIs like cpumask_next and cpumask_set_cpu never access > bits beyond cpu count, cpumask_size() bytes of memory is enough > > Signed-off-by: Eddy Tao Hi Eddy, Thanks for this patch, I have one small nit, but the rest looks good. Acked-by: Eelco Chaudron > --- > net/openvswitch/flow.c | 9 ++++++--- > net/openvswitch/flow.h | 2 +- > net/openvswitch/flow_table.c | 8 +++++--- > 3 files changed, 12 insertions(+), 7 deletions(-) > > diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c > index e20d1a973417..416976f70322 100644 > --- a/net/openvswitch/flow.c > +++ b/net/openvswitch/flow.c > @@ -107,7 +107,8 @@ void ovs_flow_stats_update(struct sw_flow *flow, __= be16 tcp_flags, > > rcu_assign_pointer(flow->stats[cpu], > new_stats); > - cpumask_set_cpu(cpu, &flow->cpu_used_mask); > + cpumask_set_cpu(cpu, > + flow->cpu_used_mask); > goto unlock; > } > } > @@ -135,7 +136,8 @@ void ovs_flow_stats_get(const struct sw_flow *flow,= > memset(ovs_stats, 0, sizeof(*ovs_stats)); > > /* We open code this to make sure cpu 0 is always considered */ > - for (cpu =3D 0; cpu < nr_cpu_ids; cpu =3D cpumask_next(cpu, &flow->cp= u_used_mask)) { > + for (cpu =3D 0; cpu < nr_cpu_ids; > + cpu =3D cpumask_next(cpu, flow->cpu_used_mask)) { > struct sw_flow_stats *stats =3D rcu_dereference_ovsl(flow->stats[cpu= ]); > > if (stats) { > @@ -159,7 +161,8 @@ void ovs_flow_stats_clear(struct sw_flow *flow) > int cpu; > > /* We open code this to make sure cpu 0 is always considered */ > - for (cpu =3D 0; cpu < nr_cpu_ids; cpu =3D cpumask_next(cpu, &flow->cp= u_used_mask)) { > + for (cpu =3D 0; cpu < nr_cpu_ids; > + cpu =3D cpumask_next(cpu, flow->cpu_used_mask)) { > struct sw_flow_stats *stats =3D ovsl_dereference(flow->stats[cpu]); > > if (stats) { > diff --git a/net/openvswitch/flow.h b/net/openvswitch/flow.h > index 073ab73ffeaa..b5711aff6e76 100644 > --- a/net/openvswitch/flow.h > +++ b/net/openvswitch/flow.h > @@ -229,7 +229,7 @@ struct sw_flow { > */ > struct sw_flow_key key; > struct sw_flow_id id; > - struct cpumask cpu_used_mask; > + struct cpumask *cpu_used_mask; > struct sw_flow_mask *mask; > struct sw_flow_actions __rcu *sf_acts; > struct sw_flow_stats __rcu *stats[]; /* One for each CPU. First one > diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.= c > index 0a0e4c283f02..dc6a174c3194 100644 > --- a/net/openvswitch/flow_table.c > +++ b/net/openvswitch/flow_table.c > @@ -87,11 +87,12 @@ struct sw_flow *ovs_flow_alloc(void) > if (!stats) > goto err; > > + flow->cpu_used_mask =3D (struct cpumask *)&flow->stats[nr_cpu_ids]; nit: I would move this up with the other flow structure initialisation. diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c index dc6a174c3194..791504b7f42b 100644 --- a/net/openvswitch/flow_table.c +++ b/net/openvswitch/flow_table.c @@ -79,6 +79,7 @@ struct sw_flow *ovs_flow_alloc(void) return ERR_PTR(-ENOMEM); flow->stats_last_writer =3D -1; + flow->cpu_used_mask =3D (struct cpumask *)&flow->stats[nr_cpu_ids= ]; /* Initialize the default stat node. */ stats =3D kmem_cache_alloc_node(flow_stats_cache, @@ -87,7 +88,6 @@ struct sw_flow *ovs_flow_alloc(void) if (!stats) goto err; - flow->cpu_used_mask =3D (struct cpumask *)&flow->stats[nr_cpu_ids= ]; spin_lock_init(&stats->lock); > spin_lock_init(&stats->lock); > > RCU_INIT_POINTER(flow->stats[0], stats); > > - cpumask_set_cpu(0, &flow->cpu_used_mask); > + cpumask_set_cpu(0, flow->cpu_used_mask); > > return flow; > err: > @@ -115,7 +116,7 @@ static void flow_free(struct sw_flow *flow) > flow->sf_acts); > /* We open code this to make sure cpu 0 is always considered */ > for (cpu =3D 0; cpu < nr_cpu_ids; > - cpu =3D cpumask_next(cpu, &flow->cpu_used_mask)) { > + cpu =3D cpumask_next(cpu, flow->cpu_used_mask)) { > if (flow->stats[cpu]) > kmem_cache_free(flow_stats_cache, > (struct sw_flow_stats __force *)flow->stats[cpu]); > @@ -1196,7 +1197,8 @@ int ovs_flow_init(void) > > flow_cache =3D kmem_cache_create("sw_flow", sizeof(struct sw_flow) > + (nr_cpu_ids > - * sizeof(struct sw_flow_stats *)), > + * sizeof(struct sw_flow_stats *)) > + + cpumask_size(), > 0, 0, NULL); > if (flow_cache =3D=3D NULL) > return -ENOMEM; > -- = > 2.27.0