Subject: Re: [PATCH v3 5/5] bonding: Add tlb_dynamic_lb module parameter

From: Nikolay Aleksandrov <[email-masked]>
Date: Wed, 02 Apr 2014 12:47:12 +0200

On 04/02/2014 09:00 AM, Mahesh Bandewar wrote:
> The aggresive load balancing causes packet re-ordering as active
> flows are moved from a slave to another within the group. Sometime
> this aggresive lb is not necessary if the preference is for less
> re-ordering. This module parameter if used with value "0" disables
> this dynamic flow shuffling minimizing packet re-ordering. Of course
> the side effect is that it has to live with the static load balancing
> that the hashing distribution provides. This impact is less severe if
> the correct xmit-hashing-policy is used for the tlb setup.
> 
> The default value of the parameter is set to "1" mimicing the earlier
> behavior.
> 
> Ran the netperf test with 200 stream for 1 min between two hosts with
> 4x1G trunk (xmit-lb mode with xmit-policy L3+4) before and after these
> changes. Following was the command used for those 200 instances -
> 
>     netperf -t TCP_RR -l 60 -s 5 -H <host> -- -r81920,81920
> 
> Transactions per second:
>     Before change: 1,367.11
>     After  change: 1,470.65
> 
> Change-Id: Ie3f75c77282cf602e83a6e833c6eb164e72a0990
> Signed-off-by: Mahesh Bandewar <[email-masked]>
> ---
> v2:
>   [Trivial] Commit log update with the proper workload and perf numbers.
> v3:
>   [Trivial] Styling changes.
>   Simplified set() by using built-in BOND_OPTFLAG_IFDOWN flag. 
> 
>  drivers/net/bonding/bond_alb.c     | 19 +++++++++++++++----
>  drivers/net/bonding/bond_main.c    | 28 +++++++++++++++++++++++++---
>  drivers/net/bonding/bond_options.c | 27 +++++++++++++++++++++++++++
>  drivers/net/bonding/bond_options.h |  1 +
>  drivers/net/bonding/bond_sysfs.c   | 29 +++++++++++++++++++++++++++++
>  drivers/net/bonding/bonding.h      |  1 +
>  6 files changed, 98 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
> index bf44ab417c54..f29ec54faaf0 100644
> --- a/drivers/net/bonding/bond_alb.c
> +++ b/drivers/net/bonding/bond_alb.c
> @@ -1356,7 +1356,8 @@ static int bond_do_alb_xmit(struct sk_buff *skb, struct bonding *bond,
>  	if (!tx_slave) {
>  		/* unbalanced or unassigned, send through primary */
>  		tx_slave = rcu_dereference(bond->curr_active_slave);
> -		bond_info->unbalanced_load += skb->len;
> +		if (bond->params.tlb_dynamic_lb)
> +			bond_info->unbalanced_load += skb->len;
>  	}
>  
>  	if (tx_slave && SLAVE_IS_OK(tx_slave)) {
> @@ -1369,7 +1370,7 @@ static int bond_do_alb_xmit(struct sk_buff *skb, struct bonding *bond,
>  		goto out;
>  	}
>  
> -	if (tx_slave) {
> +	if (tx_slave && bond->params.tlb_dynamic_lb) {
>  		_lock_tx_hashtbl(bond);
>  		__tlb_clear_slave(bond, tx_slave, 0);
>  		_unlock_tx_hashtbl(bond);
> @@ -1399,11 +1400,21 @@ int bond_tlb_xmit(struct sk_buff *skb, struct net_device *bond_dev)
>  		    /* In case of IPX, it will falback to L2 hash */
>  		case htons(ETH_P_IPV6):
>  			hash_index = bond_xmit_hash(bond, skb);
> -			tx_slave = tlb_choose_channel(bond, hash_index & 0xFF, skb->len);
> +			if (bond->params.tlb_dynamic_lb) {
> +				tx_slave = tlb_choose_channel(bond,
> +							      hash_index & 0xFF,
> +							      skb->len);
> +			} else {
> +				struct list_head *iter;
> +
> +				int idx = hash_index % bond->slave_cnt;
				^^^^^^^^^^^^
This is also a declaration, please move it up and leave the empty line after it.

> +				bond_for_each_slave_rcu(bond, tx_slave, iter)
> +					if (--idx < 0)
> +						break;
> +			}
>  			break;
>  		}
>  	}
> -
>  	return bond_do_alb_xmit(skb, bond, tx_slave);
>  }
>  
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 1bff382d9291..977f688c2724 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -111,6 +111,7 @@ static struct bond_params bonding_defaults;
>  static int resend_igmp = BOND_DEFAULT_RESEND_IGMP;
>  static int packets_per_slave = 1;
>  static int lp_interval = BOND_ALB_DEFAULT_LP_INTERVAL;
> +static int tlb_dynamic_lb = 1;
>  
>  module_param(max_bonds, int, 0);
>  MODULE_PARM_DESC(max_bonds, "Max number of bonded devices");
> @@ -191,6 +192,9 @@ module_param(lp_interval, uint, 0);
>  MODULE_PARM_DESC(lp_interval, "The number of seconds between instances where "
>  			      "the bonding driver sends learning packets to "
>  			      "each slaves peer switch. The default is 1.");
> +module_param(tlb_dynamic_lb, int, 0644);
> +MODULE_PARM_DESC(tlb_dynamic_lb, "Enable periodic flow balancing. "
> +				 "The default is 1.");
>  
>  /*----------------------------- Global variables ----------------------------*/
>  
> @@ -3046,7 +3050,7 @@ static void bond_work_init_all(struct bonding *bond)
>  {
>  	INIT_DELAYED_WORK(&bond->mcast_work,
>  			  bond_resend_igmp_join_requests_delayed);
> -	if (bond_is_lb(bond))
> +	if (bond_is_lb(bond) && bond->params.tlb_dynamic_lb)
>  		INIT_DELAYED_WORK(&bond->alb_work, bond_alb_monitor);
>  	INIT_DELAYED_WORK(&bond->mii_work, bond_mii_monitor);
>  	if (bond->params.mode == BOND_MODE_ACTIVEBACKUP)
> @@ -3060,7 +3064,7 @@ static void bond_work_cancel_all(struct bonding *bond)
>  {
>  	cancel_delayed_work_sync(&bond->mii_work);
>  	cancel_delayed_work_sync(&bond->arp_work);
> -	if (bond_is_lb(bond))
> +	if (bond_is_lb(bond) && bond->params.tlb_dynamic_lb)
>  		cancel_delayed_work_sync(&bond->alb_work);
>  	cancel_delayed_work_sync(&bond->ad_work);
>  	cancel_delayed_work_sync(&bond->mcast_work);
> @@ -3098,7 +3102,8 @@ static int bond_open(struct net_device *bond_dev)
>  		 */
>  		if (bond_alb_initialize(bond, (bond->params.mode == BOND_MODE_ALB)))
>  			return -ENOMEM;
> -		queue_delayed_work(bond->wq, &bond->alb_work, 0);
> +		if (bond->params.tlb_dynamic_lb)
> +			queue_delayed_work(bond->wq, &bond->alb_work, 0);
>  	}
>  
>  	if (bond->params.miimon)  /* link check interval, in milliseconds. */
> @@ -4285,6 +4290,22 @@ static int bond_check_params(struct bond_params *params)
>  		lp_interval = BOND_ALB_DEFAULT_LP_INTERVAL;
>  	}
>  
> +	if (!tlb_dynamic_lb) {
> +		if (bond_mode == BOND_MODE_TLB) {
> +			pr_notice("Dynamic-lb is disabled.\n");
> +		} else {
> +			pr_warn("Disabling dynamic-lb is unsupported"
> +				" in this mode, force enabling "
> +				"dynamic-lb\n");
			^^^^^^
Please keep the messages on a single line even if it's a bit longer, that way
it's easier to grep.

> +			/*
> +			 * IMPORTANT: Set it to "1" here so that we
> +			 * dont have to worry about validating mode
> +			 * before checking value of tlb_dynamic_lb
> +			 */
			^^^^^
In the networking the comment style is /* text
					* text
					*/
(Documentation/networking/netdev-FAQ.txt)
> +			tlb_dynamic_lb = 1;
> +		}
> +	}
> +
>  	/* fill params struct with the proper values */
>  	params->mode = bond_mode;
>  	params->xmit_policy = xmit_hashtype;
> @@ -4306,6 +4327,7 @@ static int bond_check_params(struct bond_params *params)
>  	params->min_links = min_links;
>  	params->lp_interval = lp_interval;
>  	params->packets_per_slave = packets_per_slave;
> +	params->tlb_dynamic_lb = tlb_dynamic_lb;
>  	if (packets_per_slave > 0) {
>  		params->reciprocal_packets_per_slave =
>  			reciprocal_value(packets_per_slave);
> diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
> index dc3893841752..9fba7a1e6d51 100644
> --- a/drivers/net/bonding/bond_options.c
> +++ b/drivers/net/bonding/bond_options.c
> @@ -70,6 +70,8 @@ static int bond_option_mode_set(struct bonding *bond,
>  				const struct bond_opt_value *newval);
>  static int bond_option_slaves_set(struct bonding *bond,
>  				  const struct bond_opt_value *newval);
> +static int bond_option_tlb_dynamic_lb_set(struct bonding *bond,
> +				  const struct bond_opt_value *newval);
>  
>  
>  static const struct bond_opt_value bond_mode_tbl[] = {
> @@ -179,6 +181,12 @@ static const struct bond_opt_value bond_lp_interval_tbl[] = {
>  	{ NULL,      -1,      0},
>  };
>  
> +static const struct bond_opt_value bond_tlb_dynamic_lb_tbl[] = {
> +	{ "off", 0,  0},
> +	{ "on",  1,  BOND_VALFLAG_DEFAULT},
> +	{ NULL,  -1, 0}
> +};
> +
>  static const struct bond_option bond_opts[] = {
>  	[BOND_OPT_MODE] = {
>  		.id = BOND_OPT_MODE,
> @@ -364,6 +372,15 @@ static const struct bond_option bond_opts[] = {
>  		.flags = BOND_OPTFLAG_RAWVAL,
>  		.set = bond_option_slaves_set
>  	},
> +	[BOND_OPT_TLB_DYNAMIC_LB] = {
> +		.id = BOND_OPT_TLB_DYNAMIC_LB,
> +		.name = "dynamic_lb",
> +		.desc = "Enable dynamic flow shuffling",
> +		.unsuppmodes = BOND_MODE_ALL_EX(BIT(BOND_MODE_TLB)),
> +		.values = bond_tlb_dynamic_lb_tbl,
> +		.flags = BOND_OPTFLAG_IFDOWN,
> +		.set = bond_option_tlb_dynamic_lb_set,
> +	},
>  	{ }
>  };
>  
> @@ -1337,3 +1354,13 @@ err_no_cmd:
>  	ret = -EPERM;
>  	goto out;
>  }
> +
> +static int bond_option_tlb_dynamic_lb_set(struct bonding *bond,
> +					  const struct bond_opt_value *newval)
> +{
> +	pr_info("%s: Setting dynamic-lb to %s (%llu)\n",
> +		bond->dev->name, newval->string, newval->value);
> +	bond->params.tlb_dynamic_lb = newval->value;
> +
> +	return 0;
> +}
> diff --git a/drivers/net/bonding/bond_options.h b/drivers/net/bonding/bond_options.h
> index 12be9e1bfb0c..c1860f06145a 100644
> --- a/drivers/net/bonding/bond_options.h
> +++ b/drivers/net/bonding/bond_options.h
> @@ -62,6 +62,7 @@ enum {
>  	BOND_OPT_RESEND_IGMP,
>  	BOND_OPT_LP_INTERVAL,
>  	BOND_OPT_SLAVES,
> +	BOND_OPT_TLB_DYNAMIC_LB,
>  	BOND_OPT_LAST
>  };
>  
> diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
> index 0e8b268da0a0..431892f1a4ce 100644
> --- a/drivers/net/bonding/bond_sysfs.c
> +++ b/drivers/net/bonding/bond_sysfs.c
> @@ -1039,6 +1039,34 @@ static ssize_t bonding_store_lp_interval(struct device *d,
>  static DEVICE_ATTR(lp_interval, S_IRUGO | S_IWUSR,
>  		   bonding_show_lp_interval, bonding_store_lp_interval);
>  
> +static ssize_t bonding_show_tlb_dynamic_lb(struct device *d,
> +					   struct device_attribute *attr,
> +					   char *buf)
> +{
> +	struct bonding *bond = to_bond(d);
> +	return sprintf(buf, "%d\n", bond->params.tlb_dynamic_lb);
> +}
> +
> +static ssize_t bonding_store_tlb_dynamic_lb(struct device *d,
> +					    struct device_attribute *attr,
> +					    const char *buf,
> +					    size_t count)
> +{
> +	struct bonding *bond = to_bond(d);
> +	int ret;
> +
> +	ret = bond_opt_tryset_rtnl(bond, BOND_OPT_TLB_DYNAMIC_LB,
> +				   (char *)buf);
> +	if (!ret)
> +		ret = count;
> +
> +	return ret;
> +}
> +
> +static DEVICE_ATTR(tlb_dynamic_lb, S_IRUGO | S_IWUSR,
> +		   bonding_show_tlb_dynamic_lb,
> +		   bonding_store_tlb_dynamic_lb);
> +
>  static ssize_t bonding_show_packets_per_slave(struct device *d,
>  					      struct device_attribute *attr,
>  					      char *buf)
> @@ -1099,6 +1127,7 @@ static struct attribute *per_bond_attrs[] = {
>  	&dev_attr_min_links.attr,
>  	&dev_attr_lp_interval.attr,
>  	&dev_attr_packets_per_slave.attr,
> +	&dev_attr_tlb_dynamic_lb.attr,
>  	NULL,
>  };
>  
> diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
> index c0948ca26389..c1c7c2f12ac4 100644
> --- a/drivers/net/bonding/bonding.h
> +++ b/drivers/net/bonding/bonding.h
> @@ -174,6 +174,7 @@ struct bond_params {
>  	int resend_igmp;
>  	int lp_interval;
>  	int packets_per_slave;
> +	int tlb_dynamic_lb;
>  	struct reciprocal_value reciprocal_packets_per_slave;
>  };
>  
>