Messages in this thread | | | Date | Mon, 14 Apr 2014 00:19:14 -0400 | From | Steven Galgano <> | Subject | Re: [PATCH v2] tuntap: add flow control to support back pressure |
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On 04/13/2014 09:40 PM, David Miller wrote: > From: Steven Galgano <sgalgano@adjacentlink.com> > Date: Sun, 13 Apr 2014 21:30:27 -0400 > >> Added optional per queue flow control support using IFF_FLOW_CONTROL. When the IFF_FLOW_CONTROL TUNSETIFF flag is specified it will set a per queue flag to indicate that the queue should be stopped using netif_tx_stop_queue(), rather than discarding frames once full. After reading a frame from the respective stopped queue, a netif_tx_wake_queue() is issued to signal resource availability. >> >> The per queue TUN_FLOW_CONTROL flag is stored in struct tun_file. This provides the flexibility to enable flow control on all, none or some queues when using IFF_MULTI_QUEUE. When not using IFF_MULTI_QUEUE, IFF_FLOW_CONTROL will apply to the single queue. No changes were made to the default drop frame policy. >> >> This change adds support for back pressure use cases. >> >> Reported-by: Brian Adamson <brian.adamson@nrl.navy.mil> >> Tested-by: Joseph Giovatto <jgiovatto@djacentlink.com> >> Signed-off-by: Steven Galgano <sgalgano@adjacentlink.com> > > Please format your commit messages to ~80 columns of text. > > It won't be automatically formatted by GIT and in fact it looks ugly > with all the wrapping in text based tools. > Added optional per queue flow control support using IFF_FLOW_CONTROL. When the IFF_FLOW_CONTROL TUNSETIFF flag is specified it will set a per queue flag to indicate that the queue should be stopped using netif_tx_stop_queue(), rather than discarding frames once full. After reading a frame from the respective stopped queue, a netif_tx_wake_queue() is issued to signal resource availability.
The per queue TUN_FLOW_CONTROL flag is stored in struct tun_file. This provides the flexibility to enable flow control on all, none or some queues when using IFF_MULTI_QUEUE. When not using IFF_MULTI_QUEUE, IFF_FLOW_CONTROL will apply to the single queue. No changes were made to the default drop frame policy.
This change adds support for back pressure use cases.
Reported-by: Brian Adamson <brian.adamson@nrl.navy.mil> Tested-by: Joseph Giovatto <jgiovatto@djacentlink.com> Signed-off-by: Steven Galgano <sgalgano@adjacentlink.com>
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