# Poor performance when turning HT off

**URL:** <https://forums.suse.com/t/poor-performance-when-turning-ht-off/27660>\
**Category:** SLES Configure-Administer\
**Created:** [November 23, 2015, 2:16pm UTC](https://forums.suse.com/t/poor-performance-when-turning-ht-off/27660 "2015-11-23T14:16:57Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![mradu](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mradu](https://forums.suse.com/u/mradu)\
**Post date:** [November 23, 2015, 2:16pm UTC](https://forums.suse.com/t/poor-performance-when-turning-ht-off/27660/1 "2015-11-23T14:16:57Z")

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I’m running SLES12 on a dual socket Xeon E5-2699 v3 server and I am noticing a strange behaviour of the OS. When the # of cores are all active and HT is enabled everything seems to be running fine, however when I change (through BIOS) the number of active cores or turn off HT then the OS starts to freeze for a second or so repeatedly as if it were laging however my cpu, memory, cache utilization are all very low.  
When I boot up a different distribution of linux, this behavior doesn’t repeat itself.  
Has anyone experienced this?

Thanks in advance!  
M.