Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.

RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

Description of problem:
rhel6.1 has 2 times higher UDP datagram loss when receiving 1400Bytes long datagrams over 10gig ethernet than rhel6.0

Version-Release number of selected component (if applicable):
2.6.32-131.0.1.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1.run /root/prepare_sys.py
2.run netperf -H 172.16.29.20 -t UDP_STREAM -- -m 1000

Socket  Message  Elapsed      Messages                
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec

124928    1000   10.00     5026535      0    4021.23
124928           10.00     2139250           1711.40

  
Actual results:
RHEL 6.1

Expected results:
datagram loss decreased to rhel6.0 levels

Additional info:

Please see: http://download.englab.brq.redhat.com/perf-results//netperf/RHEL61-20110413/#u6_fd29--10_to_fd29--20_tp
on this plot is shown local send throughput of rhel6.0 and 6.1. Both systems sends almost same amount of data.

On this plot http://download.englab.brq.redhat.com/perf-results//netperf/RHEL61-20110413/#u6_fd29--10_to_fd29--20_rtp received traffic is shown. Rhel6.1 receives significantly smaller amount of data.

On this plot http://download.englab.brq.redhat.com/perf-results//netperf/RHEL61-20110413/#u6_fd29--10_to_fd29--20_lt is shown how much network traffic is lost. It is clear that on rhel6.1 amount of lost traffic is much higher.

I presume the 82599 interfaces were the only ones that saw this drop?

I would be curious to know how the RHEL6.0 throughput compares to 2.6.32-71.27.1.el6 or later.  There are changes in RHEL6.1 and 2.6.32-71.27.1.el6 that fix an erratum, but likely impact performance.

Would you be able to run a similar test with RHEL6.0.z kernel 2.6.32-71.27.1.el6 or later to help verify?