| Summary: | e1000e: TX bytes stats are over-reported when NAT is enabled and used | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | James M. Leddy <james.leddy> |
| Component: | kernel | Assignee: | Flavio Leitner <fleitner> |
| Status: | CLOSED NOTABUG | QA Contact: | Network QE <network-qe> |
| Severity: | high | Docs Contact: | |
| Priority: | high | ||
| Version: | 6.1 | CC: | agospoda, arozansk, fleitner, gborsuk, james.leddy, kzhang |
| Target Milestone: | rc | ||
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | 693430 | Environment: | |
| Last Closed: | 2011-06-17 23:03:14 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Bug Depends On: | 693430 | ||
| Bug Blocks: | |||
Since RHEL 6.1 External Beta has begun, and this bug remains unresolved, it has been rejected as it is not proposed as exception or blocker. Red Hat invites you to ask your support representative to propose this request, if appropriate and relevant, in the next release of Red Hat Enterprise Linux. Flavio, I seem to remember you had a patch for this already. The brew builds referenced are gone, so please post the patch here. Thanks. If I recall the patch was based on this patch:
commit 67fd4fcb78a7ced369a6bd8a131ec8c65ebd2bbb
Author: Jeff Kirsher <jeffrey.t.kirsher>
Date: Fri Jan 7 05:12:09 2011 +0000
e1000e: convert to stats64
Actually, I was reviewing the RHEL-6 sources again and I reminded that before we cloned this ticket, I told that in RHEL-6 skb_make_writable() didn't use skb_copy() for copying skbs, so there is no skb non-linear to linear issue anymore. (ref: sf#00318121 #32 Created By: Leitner, Flavio (6/18/2010)) I just confirmed that by running the reproducer using kernel 2.6.32-131.0.15.el6.x86_64 and all the numbers are okay with e1000e. $ ethtool -i eth0 driver: e1000e version: 1.2.20-k2 firmware-version: 1.8-5 bus-info: 0000:00:19.0 <sar> 07:40:43 PM IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s 07:40:45 PM eth0 224.50 912.50 14.47 1282.28 0.00 0.00 0.00 07:40:45 PM IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s 07:40:47 PM eth0 224.00 913.00 14.44 1282.31 0.00 0.00 0.00 </sar> So, the only benefit of backporting the upstream patch would be the conversion to stats64 which RHEL-6 isn't ready yet, thus I'll close this as NotABug. Although I've been unable to spot any other way to reproduce this on RHEL-6, feel free to reopen if needed. Cheers! fbl |
Description of problem: A NAT rule might use skb_copy() which returns a linear skb. However, if the original skb is non-linear, the gso headers confuses the e1000e driver which reports the wrong number of tx bytes. The driver does: [...] segs = skb_shinfo(skb)->gso_segs ? : 1; /* multiply data chunks by size of headers */ bytecount = ((segs - 1) * skb_headlen(skb)) + skb->len; The skb_headlen() will return the full packet length for a linear skb and not just the packet headers. As the segs is not 0 because before it was a non-linear, then the driver will actually multiply the total packet length by the number of segs which is clearly incorrect. Version-Release number of selected component (if applicable): 2.6.18-254.el5 How reproducible: Always Steps to Reproduce: 1. on the server, add the iptables rule and run the tcp_send.pl reproducer 2. on the client, run the tcp_client.pl 3. compare the statistics when the client connects to the original port with the redirected port. Server: # iptables -t nat -A PREROUTING -p tcp --tcp-flags FIN,SYN,RST,ACK SYN --dport 8888 -j REDIRECT --to-ports 8877 # ./tcp_send.pl -p 8877 & client connecting directly: $ ./tcp_receive.pl -s server_ip:8877 10m or client connecting to the redirected port: $ ./tcp_receive.pl -s server_ip:8877 10m Actual results: This is when connecting directly: # sar -n DEV 2 2 | egrep 'IFACE|eth2' Average: IFACE rxpck/s txpck/s rxbyt/s txbyt/s rxcmp/s txcmp/s rxmcst/s Average: eth2 415.25 912.25 27406.50 1312921.50 0.00 0.00 0.00 This is when connecting to the redirected port: Average: eth2 415.50 914.50 27421.50 8838014.00 0.00 0.00 0.00 Expected results: The same amount to be reported.