Bug 7463 - Performance issue on Linux
Summary: Performance issue on Linux
Alias: None
Product: ThinLinc
Classification: Unclassified
Component: VNC (show other bugs)
Version: trunk
Hardware: PC Unknown
: P2 Normal
Target Milestone: 4.12.0
Assignee: Pierre Ossman
Keywords: prosaic
Depends on: 7373
Blocks: performance
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Reported: 2020-01-14 14:55 CET by Pierre Ossman
Modified: 2020-01-23 13:06 CET (History)
0 users

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Description Pierre Ossman cendio 2020-01-14 14:55:16 CET
We got a performance regression from bug 7379 where the Linux client stopped using shared memory for graphics updates. This can result in excessive CPU usage and possibly poor performance.

Already fixed upstream though:

Comment 1 Pierre Ossman cendio 2020-01-23 11:13:21 CET
Issue originally reported here:


Unfortunately he did not describe the scenario where he saw this.
Comment 2 Pierre Ossman cendio 2020-01-23 13:06:36 CET
This doesn't seem to have any major effect on performance as we cannot see any clear difference in CPU usage between versions that have this bug and those that do not.

However I can see in /proc/<pid>/maps that the fixed versions have a shared memory segment, and the broken ones do not. Using "perf" I can also see __memmove_avx_unaligned_erms using 6% CPU as a result of XPutImage() being called (instead of XShmPutImage()).

I suppose that will have to be good enough testing. Not making a release note as the difference was so small.

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