linux-kernel - Re: [ovs-dev] [PATCH net-next v8 1/1] net: openvswitch: reduce cpu_used

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Message-ID: <TYWP286MB2300E219495E608BEEB9A2F8F5DA9@TYWP286MB2300.JPNP286.PROD.OUTLOOK.COM>
Date:   Mon, 6 Feb 2023 19:27:35 +0800
From:   Eddy Tao <taoyuan_eddy@...mail.com>
To:     Eelco Chaudron <echaudro@...hat.com>
Cc:     netdev@...r.kernel.org, dev@...nvswitch.org,
        linux-kernel@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [ovs-dev] [PATCH net-next v8 1/1] net: openvswitch: reduce
 cpu_used_mask memory

Yes, Eelco, this is the last revision and no further comments for 
revision came in

eddy

On 2023/2/6 19:21, Eelco Chaudron wrote:
>
> On 5 Feb 2023, at 2:35, 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.
>>   Initialization cpu_used_mask right after stats_last_writer.
>>
>> 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@...mail.com>
> The changes look good to me. Hopefully this is the last revision ;)
>
> Acked-by: Eelco Chaudron <echaudro@...hat.com>
>