Message-ID: <OS3P286MB22953C8741F17F500879FA86F5A49@OS3P286MB2295.JPNP286.PROD.OUTLOOK.COM>
Date:   Mon, 20 Feb 2023 15:11:17 +0800
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Subject: Re: [PATCH net-next v1 1/1] net: openvswitch: ovs_packet_cmd_execute
 put sw_flow mainbody in stack
Content-Language: en-US
To:     Simon Horman <simon.horman@corigine.com>
Cc:     netdev@vger.kernel.org, Pravin B Shelar <pshelar@ovn.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, dev@openvswitch.org,
        linux-kernel@vger.kernel.org
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From:   Eddy Tao <taoyuan_eddy@hotmail.com>
In-Reply-To: <Y/IqJvWEJ+UNOs6i@corigine.com>
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Hi, Simon:


     About your concern for the stack size, it leads to more room for 
improvement.

I will file a new version which will have smaller stack occupation and 
better performance


The new revision is invoked by existing examples of using struct in 
stack, in the same file net/openvswitch/datapath.c

struct sw_flow_actions *get_flow_actions(..)
{
     struct sw_flow_key masked_key;==> sizeof sw_flow_key is 464 bytes

static noinline_for_stack int
ovs_nla_init_match_and_action(..)
{
     struct sw_flow_mask mask;==> sizeof sw_flow_mask is 496 bytes


The first example reminded me, revisiting the code in 
ovs_packet_cmd_execute, basically sw_flow serves as a container for 
sw_flow_actions and sw_flow_key only.

We do not need the bulk of tunnel info memory in sw_flow, which saves us 
200+ bytes further -- less is more.


The new revision will be presented shortly after some sanity and benchmark

eddy