Messages in this thread | | | From | Eelco Chaudron <> | Subject | Re: [ovs-dev] [PATCH net-next v3 1/1] net:openvswitch:reduce cpu_used_mask memory | Date | Thu, 02 Feb 2023 14:33:06 +0100 |
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On 2 Feb 2023, at 13:40, 陶 缘 wrote:
> Hi, Eelco: > > I have a query regarding to the style check. > Though the './scripts/checkpatch.pl' emit no warning/error, the 'netdev/checkpatch' still has one warning "WARNING: line length of 82 exceeds 80 columns" > I went through the patch line by line and could not find any changed line exceeding the 80 character limit. > > I am afraid that the netdev/checkpatch takes counts on the removed line(old removed line has length exceeding 80 and i have revised that in the patch already > > Is there any known issue regarding to the netdev/checkpatch?
Not sure which netdev/checkpatch you are referring to. I always you the general kernel one in /script/checkpatch.pl.
Your patch looks good to me with /script/checkpatch.pl --strict.
> Best regards > > eddy > > ________________________________ > 发件人: Eelco Chaudron <echaudro@redhat.com> > 发送时间: 2023年2月2日 11:44 > 收件人: 陶 缘 <taoyuan_eddy@hotmail.com> > 抄送: netdev@vger.kernel.org <netdev@vger.kernel.org>; dev@openvswitch.org <dev@openvswitch.org>; linux-kernel@vger.kernel.org <linux-kernel@vger.kernel.org>; Eric Dumazet <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni <pabeni@redhat.com>; David S. Miller <davem@davemloft.net> > 主题: Re: [ovs-dev] [PATCH net-next v3 1/1] net:openvswitch:reduce cpu_used_mask memory > > > > On 2 Feb 2023, at 12:26, 陶 缘 wrote: > >> Hi, Eelco: >> >> Thanks for your time going through the detail. >> The thing is: sizeof(struct cpumask), with default CONFIG_NR_CPUS 8192, has a size of 1024 bytes even on a system with only 4 cpus. >> While in practice the cpumask APIs like cpumask_next and cpumask_set_cpu never access more than cpumask_size() of bytes in the bitmap >> My change used cpumask_size() (in above example, consume 8 bytes after alignement for the cpumask, it saved 1016 bytes for every flow. > > I looked at the wrong nr_cpumask_bits definition, so thanks for this education :) > >> Your question reminded me to revisit the description "as well as the iteration of bits in cpu_used_mask", after a second think, this statement is not valid and should be removed. >> since the iteration API will not access the number of bytes decided by nr_cpu_ids(running CPUs) >> >> I will remove this statement after solving a final style issue in the next submission. > > Thanks! > > >> Thanks >> eddy >> ________________________________ >> 发件人: Eelco Chaudron <echaudro@redhat.com> >> 发送时间: 2023年2月2日 11:05 >> 收件人: Eddy Tao <taoyuan_eddy@hotmail.com> >> 抄送: netdev@vger.kernel.org <netdev@vger.kernel.org>; dev@openvswitch.org <dev@openvswitch.org>; linux-kernel@vger.kernel.org <linux-kernel@vger.kernel.org>; Eric Dumazet <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni <pabeni@redhat.com>; David S. Miller <davem@davemloft.net> >> 主题: Re: [ovs-dev] [PATCH net-next v3 1/1] net:openvswitch:reduce cpu_used_mask memory >> >> >> >> On 2 Feb 2023, at 11:32, 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 >>> as well as the iteration of bits in cpu_used_mask when handling >>> netlink message from ofproto >> >> I’m trying to understand how this will decrease memory usage. The size of the flow_cache stayed the same (actually it’s large due to the extra pointer). >> >> Also do not understand why the iteration is less, as the mask is initialized the same. >> >> Cheers, >> >> Eelco >> >>> 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 <taoyuan_eddy@hotmail.com> >>> --- >>> net/openvswitch/flow.c | 8 +++++--- >>> net/openvswitch/flow.h | 2 +- >>> net/openvswitch/flow_table.c | 8 +++++--- >>> 3 files changed, 11 insertions(+), 7 deletions(-) >>> >>> diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c >>> index e20d1a973417..0109a5f86f6a 100644 >>> --- a/net/openvswitch/flow.c >>> +++ b/net/openvswitch/flow.c >>> @@ -107,7 +107,7 @@ 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 +135,8 @@ 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 = 0; cpu < nr_cpu_ids; cpu = cpumask_next(cpu, &flow->cpu_used_mask)) { >>> + for (cpu = 0; cpu < nr_cpu_ids; >>> + cpu = cpumask_next(cpu, flow->cpu_used_mask)) { >>> struct sw_flow_stats *stats = rcu_dereference_ovsl(flow->stats[cpu]); >>> >>> if (stats) { >>> @@ -159,7 +160,8 @@ 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 = 0; cpu < nr_cpu_ids; cpu = cpumask_next(cpu, &flow->cpu_used_mask)) { >>> + for (cpu = 0; cpu < nr_cpu_ids; >>> + cpu = cpumask_next(cpu, flow->cpu_used_mask)) { >>> struct sw_flow_stats *stats = 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 = (struct cpumask *)&flow->stats[nr_cpu_ids]; >>> 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 = 0; cpu < nr_cpu_ids; >>> - cpu = cpumask_next(cpu, &flow->cpu_used_mask)) { >>> + cpu = 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 = 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 == NULL) >>> return -ENOMEM; >>> -- >>> 2.27.0 >>> >>> _______________________________________________ >>> dev mailing list >>> dev@openvswitch.org >>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
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