[Xen-devel] [RFC PATCH V2 8/8] netback: remove unwanted notification generation during NAPI processing.

[Wei Liu <wei.liu2@xxxxxxxxxx>]

In original implementation, tx_build_gops tends to update req_event
pointer every time it sees tx error or finish one batch. Remove those
code to only update req_event pointer when we really want to shut down
NAPI.

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 drivers/net/xen-netback/interface.c |    5 +++--
 drivers/net/xen-netback/netback.c   |    4 +---
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/net/xen-netback/interface.c 
b/drivers/net/xen-netback/interface.c
index 05caccc..7cf0947 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -58,8 +58,8 @@ static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
        if (xenvif_rx_schedulable(vif))
                netif_wake_queue(vif->dev);
 
-       if (likely(napi_schedule_prep(&vif->napi)))
-               __napi_schedule(&vif->napi);
+       if (RING_HAS_UNCONSUMED_REQUESTS(&vif->tx))
+               napi_schedule(&vif->napi);
 
        return IRQ_HANDLED;
 }
@@ -74,6 +74,7 @@ static int xenvif_poll(struct napi_struct *napi, int budget)
        if (work_done < budget) {
                int more_to_do = 0;
                unsigned long flag;
+
                local_irq_save(flag);
 
                RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
diff --git a/drivers/net/xen-netback/netback.c 
b/drivers/net/xen-netback/netback.c
index fa864f4..34f34f5 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -663,7 +663,6 @@ static void xenvif_tx_err(struct xenvif *vif,
                txp = RING_GET_REQUEST(&vif->tx, cons++);
        } while (1);
        vif->tx.req_cons = cons;
-       xenvif_check_rx_xenvif(vif);
 }
 
 static int xenvif_count_requests(struct xenvif *vif,
@@ -1048,7 +1047,7 @@ static unsigned xenvif_tx_build_gops(struct xenvif *vif,
                int pool_idx;
                struct pending_tx_info *pending_tx_info;
 
-               RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, work_to_do);
+               work_to_do = RING_HAS_UNCONSUMED_REQUESTS(&vif->tx);
                if (!work_to_do) {
                        break;
                }
@@ -1188,7 +1187,6 @@ static unsigned xenvif_tx_build_gops(struct xenvif *vif,
                gop = request_gop;
 
                vif->tx.req_cons = idx;
-               xenvif_check_rx_xenvif(vif);
 
                if ((gop - tco) >= MAX_PENDING_REQS)
                        break;
-- 
1.7.2.5


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