Re: [PATCH 2/3] bql: Byte queue limits

[Eric Dumazet <eric.dumazet@gmail.com>]

Le lundi 25 avril 2011 à 21:38 -0700, Tom Herbert a écrit :
> Networking stack support for byte queue limits, uses dynamic queue
> limits library.  Byte queue limits are maintained per transmit queue,
> and a bql structure has been added to netdev_queue structure for this
> purpose.
> 
> Configuration of bql is in the tx-<n> sysfs directory for the queue
> under the byte_queue_limits directory.  Configuration includes:
> limit_min, bql minimum limit
> limit_max, bql maximum limit
> hold_time, bql slack hold time
> 
> Also under the directory are:
> limit, current byte limit
> inflight, current number of bytes on the queue
> 

Wow... magical values and very limited advices how to tune them.

Tom, this reminds me you were supposed to provide Documentation/files to
describe RPS, RFS, XPS ...

We receive many questions about these features...

> Signed-off-by: Tom Herbert <therbert@google.com>
> ---
>  include/linux/netdevice.h |   46 +++++++++++++++-
>  net/core/net-sysfs.c      |  137 +++++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 177 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index cb8178a..0a76b88 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -44,6 +44,7 @@
>  #include <linux/rculist.h>
>  #include <linux/dmaengine.h>
>  #include <linux/workqueue.h>
> +#include <linux/dynamic_queue_limits.h>
>  
>  #include <linux/ethtool.h>
>  #include <net/net_namespace.h>
> @@ -556,8 +557,10 @@ struct netdev_queue {
>  	struct Qdisc		*qdisc;
>  	unsigned long		state;
>  	struct Qdisc		*qdisc_sleeping;
> -#ifdef CONFIG_RPS
> +#ifdef CONFIG_XPS
>  	struct kobject		kobj;
> +	bool			do_bql;
> +	struct dql		dql;
>  #endif

I have no idea why you use CONFIG_XPS for BQL (how BQL is it related to
SMP ???), and why kobj is now guarded by CONFIG_XPS instead of
CONFIG_RPS.