netdev - Re: [PATCH net-next 3/4] tcp: tsq: add shortcut in tcp_tasklet

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Message-ID: <1480716750.18162.387.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Fri, 02 Dec 2016 14:12:30 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 3/4] tcp: tsq: add shortcut in
 tcp_tasklet_func()

On Fri, 2016-12-02 at 10:25 -0800, Eric Dumazet wrote:
> Under high stress, I've seen tcp_tasklet_func() consuming
> ~700 usec, handling ~150 tcp sockets.
> 
> By setting TCP_TSQ_DEFERRED in tcp_wfree(), we give a chance
> for other cpus/threads entering tcp_write_xmit() to grab it,
> allowing tcp_tasklet_func() to skip sockets that already did
> an xmit cycle.
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

...

> @@ -884,7 +884,7 @@ void tcp_wfree(struct sk_buff *skb)
>  		if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED))
>  			goto out;
>  
> -		nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED;
> +		nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED | TCP_TSQ_DEFERRED;

Typo here...

Should be :
		nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED | TCPF_TSQ_DEFERRED;

>  		nval = cmpxchg(&tp->tsq_flags, oval, nval);
>  		if (nval != oval)
>  			continue;