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Message #79277
[Bug 1358949] Re: arm64 iperf performance suboptimal
This bug is awaiting verification that the kernel in -proposed solves
the problem. Please test the kernel and update this bug with the
results. If the problem is solved, change the tag 'verification-needed-
trusty' to 'verification-done-trusty'.
If verification is not done by 5 working days from today, this fix will
be dropped from the source code, and this bug will be closed.
See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how
to enable and use -proposed. Thank you!
** Tags added: verification-needed-trusty
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https://bugs.launchpad.net/bugs/1358949
Title:
arm64 iperf performance suboptimal
Status in “linux” package in Ubuntu:
Fix Released
Status in “linux” source package in Trusty:
Fix Committed
Status in “linux” source package in Utopic:
Fix Released
Bug description:
[Impact]
The copy_{to,from}_user implementations in the Ubuntu kernel are suboptimal. Optimized implementations have been submitted upstream and have shown a significant improvement in network performance.
Iperf performance increase:
-l (size) 1 core result
Optimized 64B 44-51Mb/s
1500B 4.9Gb/s
30000B 16.2Gb/s
Original 64B 34-50.7Mb/s
1500B 4.7Gb/s
30000B 14.5Gb/s
[Test Case]
Generate traffic from one node to another using iperf (see above for config).
[Regression Risk]
These functions are obviously used heavily throughout the kernel, so a defect here could have significant impact. This risk is mitigated by using an implementation heavily based on the linaro string libraries (which are used in other places already, e.g. glibc), and through active testing of this patch on real hardware using a trusty-kernel base.
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References