Bug 243848 - iperf perfoms bad with F7 kernel
iperf perfoms bad with F7 kernel
Status: CLOSED CURRENTRELEASE
Product: Fedora
Classification: Fedora
Component: kernel (Show other bugs)
7
i686 Linux
low Severity medium
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Assigned To: Kernel Maintainer List
Brian Brock
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Depends On:
Blocks:
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Reported: 2007-06-12 08:05 EDT by Michal Žejdl
Modified: 2007-11-30 17:12 EST (History)
0 users

See Also:
Fixed In Version: 2.6.22.1-41.fc7
Doc Type: Bug Fix
Doc Text:
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Last Closed: 2007-08-08 04:22:38 EDT
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RHEL 7.3 requirements from Atomic Host:
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Description Michal Žejdl 2007-06-12 08:05:56 EDT
Description of problem:
Running iperf on 100 Mbps NIC slow down system response, resulting in bad
transfer ratio (3 - 15 Mbps) in download direction, or in both direction when
"vmstat 1" is runnig. This appears since F7.

Version-Release number of selected component (if applicable):
2.6.21-1.3194.fc7

How reproducible:
always

Steps to Reproduce:
1. run vmstat 1 to make worst performance results and see what happens
2. run iperf -s on remote machine
3. run iperf -c <remote machine> -r
  
Actual results:
[  5] local 10.1.224.176 port 56235 connected with 10.1.3.77 port 5001
[  5]  0.0-10.0 sec    113 MBytes  94.5 Mbits/sec
[  4] local 10.1.224.176 port 5001 connected with 10.1.3.77 port 50328
[  4]  0.0-10.1 sec  17.0 MBytes  14.1 Mbits/sec
- vmstat shows 100% cpu used (over 90% in syscalls), system has a slow response

Expected results:
94 Mbps in both directions (iperf), more interrupts and less system time on CPU
(vmstat), normal system response

Additional info:
System with problem is laptop Acer TravelMate 290LCi with updated Fedora 7,
using 8139too module. With kernel 2.6.20-1.2952.fc6 there is no problem.

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