Thread (1 message) 1 message, 1 author, 2017-12-19

Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available

From: Stephen Hemminger <stephen@networkplumber.org>
Date: 2017-12-19 18:13:45

On Tue, 19 Dec 2017 20:07:01 +0200
"Michael S. Tsirkin" [off-list ref] wrote:
On Tue, Dec 19, 2017 at 09:55:48AM -0800, Stephen Hemminger wrote:
quoted
On Tue, 19 Dec 2017 09:41:39 -0800
"Samudrala, Sridhar" [off-list ref] wrote:
  
quoted
On 12/19/2017 7:47 AM, Michael S. Tsirkin wrote:  
quoted
I'll need to look at this more, in particular the feature
bit is missing here. For now one question:

On Mon, Dec 18, 2017 at 04:40:36PM -0800, Sridhar Samudrala wrote:    
quoted
@@ -56,6 +58,8 @@ module_param(napi_tx, bool, 0644);
   */
  DECLARE_EWMA(pkt_len, 0, 64)
  
+#define VF_TAKEOVER_INT	(HZ / 10)
+
  #define VIRTNET_DRIVER_VERSION "1.0.0"
  
  static const unsigned long guest_offloads[] = {    
Why is this delay necessary? And why by 100ms?    
This is based on netvsc implementation and here is the commit that
added this delay.  Not sure if this needs to be 100ms.

commit 6123c66854c174e4982f98195100c1d990f9e5e6
Author: stephen hemminger [off-list ref]
Date:   Wed Aug 9 17:46:03 2017 -0700

     netvsc: delay setup of VF device

     When VF device is discovered, delay bring it automatically up in
     order to allow userspace to some simple changes (like renaming).


  
could be 10ms, just enough to let udev do its renaming  
Isn't there a way not to depend on udev completing its thing within a given timeframe?
Not that I know. the path is quite indirect.
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