netdev - Re: [PATCH net-next v4 1/1] net:openvswitch:reduce cpu_used

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Message-ID: <Y9zMwA2pxSpdUdT5@nanopsycho>
Date:   Fri, 3 Feb 2023 09:58:40 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     Eddy Tao <taoyuan_eddy@...mail.com>
Cc:     netdev@...r.kernel.org, Pravin B Shelar <pshelar@....org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, dev@...nvswitch.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v4 1/1] net:openvswitch:reduce cpu_used_mask
 memory

Fri, Feb 03, 2023 at 09:40:36AM CET, taoyuan_eddy@...mail.com 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 <taoyuan_eddy@...mail.com>

Reviewed-by: Jiri Pirko <jiri@...dia.com>