Messages in this thread Patch in this message | | | Date | Wed, 16 Apr 2003 23:56:45 -0700 | From | (Don Cohen) | Subject | proposed optimization for network drivers |
| |
I notice that netif_rx (net/core/dev.c) discards packets when it's in throttle mode. However, before it does this the driver has already wasted a lot of time allocating the skb, calling eth_type_trans, etc. That effort could be saved if the driver checked throttle first.
Sample diff:
--- /usr/src/linux-2.4.18-clean/drivers/net/8139too.c Mon Feb 25 11:37:59 2002 +++ /usr/src/linux-2.4.18/drivers/net/8139too.c Wed Apr 16 23:30:30 2003 @@ -1908,6 +1908,11 @@ return; }
+ if (softnet_data[smp_processor_id()].throttle) { + dev->last_rx = jiffies; + netdev_rx_stat[smp_processor_id()].dropped++; + } else { + /* Malloc up new buffer, compatible with net-2e. */ /* Omit the four octet CRC from the length. */
@@ -1936,6 +1941,7 @@ dev->name); tp->stats.rx_dropped++; } + }
cur_rx = (cur_rx + rx_size + 4 + 3) & ~3; RTL_W16 (RxBufPtr, cur_rx - 16); Hmm, now that I notice, there is one small change in semantics here. Before every packet that was counted by netdev_rx_stat[].dropped had also been counted in stats.rx_bytes and rx_packets and this is no longer the case. If that bothers you then perhaps there should just be a separate counter for packets dropped like this.
In my limited experimentation this sort of change has significantly increased the number of packets I could process when they were arriving too fast.
Please cc me on replies. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |