On 2011-01-08 8:33 AM, greearb@xxxxxxxxxxxxxxx wrote:
From: Ben Greear<greearb@xxxxxxxxxxxxxxx>
This saves us constantly allocating large, multi-page
skbs. It should fix the order-1 allocation errors reported,
and in a 60-vif scenario, this significantly decreases CPU
utilization, and latency, and increases bandwidth.
Signed-off-by: Ben Greear<greearb@xxxxxxxxxxxxxxx>
---
:100644 100644 b2497b8... ea2f67c... M drivers/net/wireless/ath/ath9k/recv.c
drivers/net/wireless/ath/ath9k/recv.c | 92 ++++++++++++++++++++++-----------
1 files changed, 61 insertions(+), 31 deletions(-)
diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index b2497b8..ea2f67c 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -1702,42 +1704,70 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush, bool hp)
unlikely(tsf_lower - rs.rs_tstamp> 0x10000000))
rxs->mactime += 0x100000000ULL;
- /* Ensure we always have an skb to requeue once we are done
- * processing the current buffer's skb */
- requeue_skb = ath_rxbuf_alloc(common, common->rx_bufsize, GFP_ATOMIC);
-
- /* If there is no memory we ignore the current RX'd frame,
- * tell hardware it can give us a new frame using the old
- * skb and put it at the tail of the sc->rx.rxbuf list for
- * processing. */
- if (!requeue_skb)
- goto requeue;
-
- /* Unmap the frame */
- dma_unmap_single(sc->dev, bf->bf_buf_addr,
- common->rx_bufsize,
- dma_type);
+ len = rs.rs_datalen + ah->caps.rx_status_len;
+ if (use_copybreak) {
+ skb = netdev_alloc_skb(NULL, len);
+ if (!skb) {
+ skb = bf->bf_mpdu;
+ use_copybreak = false;
+ goto non_copybreak;
+ }
+ } else {
I think this should be dependent on packet size, maybe even based on the
architecture. Especially on embedded hardware, copying large frames is
probably quite a bit more expensive than allocating large buffers. Cache
sizes are small, memory access takes several cycles, especially during
concurrent DMA.
Once I'm back home, I could try a few packet size threshold to find a
sweet spot for the typical MIPS hardware that I'm playing with. I expect
a visible performance regression from this patch when applied as-is.
- Felix
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