From: Vineet Gupta <[email protected]> Date: Wed, 4 Sep 2013 18:33:11 +0530
> This came out of staring at code due to recent performance fix. > > * TX BD reclaim can call netif_wake_queue() once, outside the loop if > one/more BDs were freed, NO need to do this each iteration. > > * TX need not look at next BD to stop the netif queue. It rather be done > in the next tx call, when it actually fails as the queue seldom gets > full but the check nevertheless needs to be done for each packet Tx. > Profiled this under heavy traffic (big tar file cp, LMBench betworking > tests) and saw not a single hit to that code. > > Signed-off-by: Vineet Gupta <[email protected]> You should keep the check in the transmit queueing code as a BUG check, almost every driver has code of the form (using NIU as an example): if (niu_tx_avail(rp) <= (skb_shinfo(skb)->nr_frags + 1)) { netif_tx_stop_queue(txq); dev_err(np->device, "%s: BUG! Tx ring full when queue awake!\n", dev->name); rp->tx_errors++; return NETDEV_TX_BUSY; } and arc_emac should too. Otherwise queue management bugs are incredibly hard to diagnose. I'm not applying this patch. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
