netdev - Re: [RFC 0/7] Add support to process rx packets in thread

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Message-ID: <3ce69fb9-f340-d50d-8e77-61c7210a61c6@nbd.name>
Date:   Sun, 26 Jul 2020 10:10:15 +0200
From:   Felix Fietkau <nbd@....name>
To:     Hillf Danton <hdanton@...a.com>
Cc:     David Laight <David.Laight@...LAB.COM>,
        Andrew Lunn <andrew@...n.ch>,
        Rakesh Pillai <pillair@...eaurora.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "ath10k@...ts.infradead.org" <ath10k@...ts.infradead.org>,
        "dianders@...omium.org" <dianders@...omium.org>,
        Markus Elfring <Markus.Elfring@....de>,
        Ding Zhao Nan <oshack@...mail.com>,
        "evgreen@...omium.org" <evgreen@...omium.org>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "johannes@...solutions.net" <johannes@...solutions.net>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kvalo@...eaurora.org" <kvalo@...eaurora.org>
Subject: Re: [RFC 0/7] Add support to process rx packets in thread

On 2020-07-26 03:22, Hillf Danton wrote:
>> - add a state bit for threaded NAPI
>> - make netif_threaded_napi_add inline
>> - run queue_work outside of local_irq_save/restore (it does that
>> internally already)
>>
>> If you don't mind, I'd like to propose this to netdev soon. Can I have
>> your Signed-off-by for that?
> 
> Feel free to do that. Is it likely for me to select a Cc?
Shall I use Signed-off-by: Hillf Danton <hdanton@...a.com>?
What Cc do you want me to add?

>> ---
>> --- a/include/linux/netdevice.h
>> +++ b/include/linux/netdevice.h
>> @@ -347,6 +347,7 @@ struct napi_struct {
>>  	struct list_head	dev_list;
>>  	struct hlist_node	napi_hash_node;
>>  	unsigned int		napi_id;
>> +	struct work_struct	work;
>>  };
>>  
>>  enum {
>> @@ -357,6 +358,7 @@ enum {
>>  	NAPI_STATE_HASHED,	/* In NAPI hash (busy polling possible) */
>>  	NAPI_STATE_NO_BUSY_POLL,/* Do not add in napi_hash, no busy polling */
>>  	NAPI_STATE_IN_BUSY_POLL,/* sk_busy_loop() owns this NAPI */
>> +	NAPI_STATE_THREADED,	/* Use threaded NAPI */
>>  };
>>  
>>  enum {
>> @@ -367,6 +369,7 @@ enum {
>>  	NAPIF_STATE_HASHED	 = BIT(NAPI_STATE_HASHED),
>>  	NAPIF_STATE_NO_BUSY_POLL = BIT(NAPI_STATE_NO_BUSY_POLL),
>>  	NAPIF_STATE_IN_BUSY_POLL = BIT(NAPI_STATE_IN_BUSY_POLL),
>> +	NAPIF_STATE_THREADED	 = BIT(NAPI_STATE_THREADED),
>>  };
>>  
>>  enum gro_result {
>> @@ -2315,6 +2318,26 @@ static inline void *netdev_priv(const struct net_device *dev)
>>  void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
>>  		    int (*poll)(struct napi_struct *, int), int weight);
>>  
>> +/**
>> + *	netif_threaded_napi_add - initialize a NAPI context
>> + *	@dev:  network device
>> + *	@napi: NAPI context
>> + *	@poll: polling function
>> + *	@weight: default weight
>> + *
>> + * This variant of netif_napi_add() should be used from drivers using NAPI
>> + * with CPU intensive poll functions.
>> + * This will schedule polling from a high priority workqueue that
>> + */
>> +static inline void netif_threaded_napi_add(struct net_device *dev,
>> +					   struct napi_struct *napi,
>> +					   int (*poll)(struct napi_struct *, int),
>> +					   int weight)
>> +{
>> +	set_bit(NAPI_STATE_THREADED, &napi->state);
>> +	netif_napi_add(dev, napi, poll, weight);
>> +}
>> +
>>  /**
>>   *	netif_tx_napi_add - initialize a NAPI context
>>   *	@dev:  network device
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -158,6 +158,7 @@ static DEFINE_SPINLOCK(offload_lock);
>>  struct list_head ptype_base[PTYPE_HASH_SIZE] __read_mostly;
>>  struct list_head ptype_all __read_mostly;	/* Taps */
>>  static struct list_head offload_base __read_mostly;
>> +static struct workqueue_struct *napi_workq;
> 
> Is __read_mostly missing?
Yes, thanks. I will add that before sending the patch.

- Felix