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Re: [Xen-devel] [GIT PULL]: Netback fixes

To: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [GIT PULL]: Netback fixes
From: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Date: Wed, 19 Jan 2011 12:50:25 +0000
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, Paul Durrant <Paul.Durrant@xxxxxxxxxx>
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On Wed, 2011-01-05 at 12:53 +0000, Ian Campbell wrote:
> The following git pull request consists of Paul Durrant's 5 patches from
> before Xmas plus a new patch of my own (actually an old long forgotten
> patch) which I will post as a reply. (There is also an equivalent
> netfront fix which I will send to netdev for upstream separately).
> These patches are for the xen/next/2.6.32 branch. Although the
> preparations for upstreaming netback are progressing well I don't think
> it is a suitable base for further development yet and these fixes are
> useful in their own right (I have also included them in my upstream
> branch).

I have updated the branch with one additional patch which augments
Paul's "Remove the 500ms timeout to restart the netif queue." patch to
remove the final vestiges of the timer. The patch follows the updated
pull request below.

The following changes since commit 3af2f5d05b1236d11e952152ac1f505e6b0e8935:
  Ian Campbell (1):
        xen: netback: take net_schedule_list_lock when removing entry from 

are available in the git repository at:

  git://xenbits.xen.org/people/ianc/linux-2.6.git for-jeremy/netback

Ian Campbell (2):
      xen: netback: Drop GSO SKBs which do not have csum_blank.
      xen: netback: completely remove tx_queue_timer

Paul Durrant (5):
      xen: netback: Re-define PKT_PROT_LEN to be bigger.
      xen: netback: Don't count packets we don't actually receive.
      xen: netback: Remove the 500ms timeout to restart the netif queue.
      xen: netback: Add a missing test to tx_work_todo.
      xen: netback: Re-factor net_tx_action_dealloc() slightly.

 drivers/xen/netback/common.h    |    3 --
 drivers/xen/netback/interface.c |   13 +------
 drivers/xen/netback/netback.c   |   74 ++++++++++++++++++--------------------
 3 files changed, 36 insertions(+), 54 deletions(-)


>From c9c31adc46fbdba37801e97ae39b084eab306508 Mon Sep 17 00:00:00 2001
From: Ian Campbell <ian.campbell@xxxxxxxxxx>
Date: Wed, 19 Jan 2011 12:43:38 +0000
Subject: [PATCH] xen: netback: completely remove tx_queue_timer

"xen: netback: Remove the 500ms timeout to restart the netif queue." missed
removing the timer initialisation.

Also remove the related comment which has been obsolete since the default for
MODPARM_copy_skb was switched to true some time ago.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
 drivers/xen/netback/common.h    |    3 ---
 drivers/xen/netback/interface.c |   13 +------------
 2 files changed, 1 insertions(+), 15 deletions(-)

diff --git a/drivers/xen/netback/common.h b/drivers/xen/netback/common.h
index feacf5f..3240cdf 100644
--- a/drivers/xen/netback/common.h
+++ b/drivers/xen/netback/common.h
@@ -100,9 +100,6 @@ struct xen_netif {
        unsigned long   remaining_credit;
        struct timer_list credit_timeout;
-       /* Enforce draining of the transmit queue. */
-       struct timer_list tx_queue_timeout;
        /* Statistics */
        int nr_copied_skbs;
diff --git a/drivers/xen/netback/interface.c b/drivers/xen/netback/interface.c
index 2e8508a..efdc21c 100644
--- a/drivers/xen/netback/interface.c
+++ b/drivers/xen/netback/interface.c
@@ -41,15 +41,7 @@
  * Module parameter 'queue_length':
  * Enables queuing in the network stack when a client has run out of receive
- * descriptors. Although this feature can improve receive bandwidth by avoiding
- * packet loss, it can also result in packets sitting in the 'tx_queue' for
- * unbounded time. This is bad if those packets hold onto foreign resources.
- * For example, consider a packet that holds onto resources belonging to the
- * guest for which it is queued (e.g., packet received on vif1.0, destined for
- * vif1.1 which is not activated in the guest): in this situation the guest
- * will never be destroyed, unless vif1.1 is taken down. To avoid this, we
- * run a timer (tx_queue_timeout) to drain the queue when the interface is
- * blocked.
+ * descriptors.
 static unsigned long netbk_queue_length = 32;
 module_param_named(queue_length, netbk_queue_length, ulong, 0644);
@@ -295,8 +287,6 @@ struct xen_netif *netif_alloc(struct device *parent, 
domid_t domid, unsigned int
        /* Initialize 'expires' now: it's used to track the credit window. */
        netif->credit_timeout.expires = jiffies;
-       init_timer(&netif->tx_queue_timeout);
        dev->netdev_ops = &netback_ops;
        SET_ETHTOOL_OPS(dev, &network_ethtool_ops);
@@ -458,7 +448,6 @@ void netif_disconnect(struct xen_netif *netif)
        wait_event(netif->waiting_to_free, atomic_read(&netif->refcnt) == 0);
-       del_timer_sync(&netif->tx_queue_timeout);
        if (netif->irq)
                unbind_from_irqhandler(netif->irq, netif);

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