On 11/19/20 3:43 AM, ljp wrote:
On 2020-11-18 19:12, Thomas Falcon wrote:
From: "Dwip N. Banerjee" <dnban...@us.ibm.com>

Reduce the amount of time spent replenishing RX buffers by
only doing so once available buffers has fallen under a certain
threshold, in this case half of the total number of buffers, or
if the polling loop exits before the packets processed is less
than its budget.

Signed-off-by: Dwip N. Banerjee <dnban...@us.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c
b/drivers/net/ethernet/ibm/ibmvnic.c
index 96df6d8fa277..9fe43ab0496d 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -2537,7 +2537,10 @@ static int ibmvnic_poll(struct napi_struct
*napi, int budget)
         frames_processed++;
     }

-    if (adapter->state != VNIC_CLOSING)
+    if (adapter->state != VNIC_CLOSING &&
+ ((atomic_read(&adapter->rx_pool[scrq_num].available) <
+          adapter->req_rx_add_entries_per_subcrq / 2) ||
+          frames_processed < budget))

1/2 seems a simple and good algorithm.
Explaining why "frames_process < budget" is necessary in the commit message
or source code also helps.

Hello, Lijun. The patch author, Dwip Banerjee, suggested the modified commit message below:

Reduce the amount of time spent replenishing RX buffers by
only doing so once available buffers has fallen under a certain
threshold, in this case half of the total number of buffers, or
if the polling loop exits before the packets processed is less
than its budget. Non-exhaustion of NAPI budget implies lower
incoming packet pressure, allowing the leeway to refill the buffers
in preparation for any impending burst.

Would such an update require a v3?


         replenish_rx_pool(adapter, &adapter->rx_pool[scrq_num]);
     if (frames_processed < budget) {
         if (napi_complete_done(napi, frames_processed)) {

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