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Message-ID: <46C7ADD6.5080707@gmail.com> Date: Sat, 18 Aug 2007 19:41:26 -0700 From: Bruce Cole <bacole@...il.com> To: Francois Romieu <romieu@...zoreil.com> CC: netdev@...r.kernel.org, bacole@...il.com, David Gundersen <gundy@...et.net.au> Subject: Re: [RFT] r8169 changes against 2.6.23-rc3 Francois Romieu wrote: > The latest serie of r8169 changes is available against 2.6.23-rc3 as: > http://www.fr.zoreil.com/people/francois/misc/20070818-2.6.23-rc3-r8169-test.patch > > or (tarball sits one level higher): > > http://www.fr.zoreil.com/linux/kernel/2.6.x/2.6.23-rc3/r8169-20070818/ > > or (rebase prone branch) > I applied these patches (except for the eeprom read support patch) to 2.6.23-rc3, and it did not fix the TX performance problem. The busy-wait workaround is still required to dramatically improve performance. I experimented some more and found that ndelay(10) is a sufficient delay within the for loop, as David Gundersen suggested. With some diagnostic code, I can see that when there is a NPQ problem, the busy wait calls ndelay(10) 4 or 5 times before the NPQ bit clears, and meanwhile the TX queue only contains a low number of entries (2 to 5 typically). This is a bit surprising, I would have guessed the root problem related to the queue filling up. I was then suspicious that maybe there was an issue with TX interrupts not being serviced in a timely manner due to the NAPI RX support, but making the TX processing work without NAPI did not solve things. I took a look at tcpdump output from both the sender&receiver and found that when there is a problem, the sender is apparently delaying transmission of packets. TCP then retransmits, and duplicate TCP sequences arrive at the receiver at that later time. So it seems that when the driver tries to queue a packet while the controller is busy processing the queue, the newly queued packet does not get noticed by the controller (until further packet activity occurs). Perhaps there is a problem with the memory barriers when adding to the TX queue, but I'm a newbie on linux kernel memory barriers. tcpdump sample follows, with the realtek interface on the sending side. In the sample, notice that the data at sequence #1429358 is retransmitted by the sender after .3 seconds, but the receiver receives both copies at basically the same time (delayed by approximately .3 seconds). Sender: 13:42:10.325958 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1414878:1416326(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:10.325979 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1416326:1417774(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:10.325999 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1417774:1419222(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:10.326018 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1419222:1420670(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:10.326036 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1420670:1422118(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:10.326056 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1422118:1423566(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:10.326076 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1423566:1425014(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:10.326094 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1425014:1426462(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:10.326114 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1426462:1427910(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:10.326565 IP 192.168.1.12.60994 > 192.168.1.11.netbios-ssn: . ack 1417774 win 2056 <nop,nop,timestamp 4346009 226653029> 13:42:10.326607 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1427910:1429358 (1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:10.326614 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1429358:1430806(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:10.326620 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: P 1430806:1431325(519) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:10.326626 IP 192.168.1.12.60994 > 192.168.1.11.netbios-ssn: . ack 1427910 win 1907 <nop,nop,timestamp 4346009 226653029> 13:42:10.366646 IP 192.168.1.12.60994 > 192.168.1.11.netbios-ssn: . ack 1429358 win 2056 <nop,nop,timestamp 4346050 226653029> 13:42:10.652691 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1429358:1430806(1448) ack 5775 win 54 <nop,nop,timestamp 226653356 4346050> NBT Session Packet: Session Message 13:42:10.653636 IP 192.168.1.12.60994 > 192.168.1.11.netbios-ssn: . ack 1430806 win 2056 <nop,nop,timestamp 4346337 226653029> 13:42:10.653671 IP 192.168.1.12.60994 > 192.168.1.11.netbios-ssn: . ack 1431325 win 2056 <nop,nop,timestamp 4346337 226653029> 13:42:10.653698 IP 192.168.1.12.60994 > 192.168.1.11.netbios-ssn: . ack 1431325 win 2056 <nop,nop,timestamp 4346337 226653029,nop,nop,sack 1 {1429358:1430806}> Receiver: 13:42:11.516820 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1414878:1416326(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:11.516841 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1416326:1417774(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:11.516856 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1417774:1419222(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:11.516881 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1419222:1420670(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:11.516895 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1420670:1422118(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:11.516923 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1422118:1423566(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:11.516938 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1423566:1425014(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:11.516952 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1425014:1426462(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:11.516975 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1426462:1427910(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:11.517148 IP 192.168.1.12.60994 > 192.168.1.11.netbios-ssn: . ack 1417774 win 2056 <nop,nop,timestamp 4346009 226653029> 13:42:11.517173 IP 192.168.1.12.60994 > 192.168.1.11.netbios-ssn: . ack 1427910 win 1907 <nop,nop,timestamp 4346009 226653029> 13:42:11.517471 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1427910:1429358(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:11.557260 IP 192.168.1.12.60994 > 192.168.1.11.netbios-ssn: . ack 1429358 win 2056 <nop,nop,timestamp 4346050 226653029> 13:42:11.843655 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1429358:1430806(1448) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:11.843704 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: P 1430806:1431325(519) ack 5775 win 54 <nop,nop,timestamp 226653029 4346009> NBT Session Packet: Session Message 13:42:11.843720 IP 192.168.1.11.netbios-ssn > 192.168.1.12.60994: . 1429358:1430806(1448) ack 5775 win 54 <nop,nop,timestamp 226653356 4346050> NBT Session Packet: Session Message 13:42:11.844342 IP 192.168.1.12.60994 > 192.168.1.11.netbios-ssn: . ack 1430806 win 2056 <nop,nop,timestamp 4346337 226653029> 13:42:11.844366 IP 192.168.1.12.60994 > 192.168.1.11.netbios-ssn: . ack 1431325 win 2056 <nop,nop,timestamp 4346337 226653029> 13:42:11.844383 IP 192.168.1.12.60994 > 192.168.1.11.netbios-ssn: . ack 1431325 win 2056 <nop,nop,timestamp 4346337 226653029,nop,nop,sack 1 {1429358:1430806}> - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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