mariadb kb on hyperthreading
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I've just noticed this paragraph: https://mariadb.com/kb/en/mariadb-memory-allocation/#hyperthreading-and-mult... 1) "HyperThreading is great for marketing, lousy for performance. It involves having two processing units sharing a single hardware cache. If both units are doing the same thing, the cache will be reasonably useful. If the units are doing different things, they will be clobbering each other's cache entries." I believe it is entirely based on a misconception: HTT has nothing to do with threads "doing the same thing". 2) About the part that warns us from using too many cores: I believe it was correct some years ago, but not today, or at least not for just 8 cores. * I don't feel comfortable deleting what others wrote, so I'll just raise the problems here. Federico -- Federico Razzoli Vettabase Ltd director & founder, Database Consultant https://vettabase.com federico.razzoli@vettabase.com +44 7739 427279 Telegram: federico_razzoli Skype: fede.razzoli The information in this e-mail and any attachments may be confidential. If you received it by mistake, please inform the sender. Unless you are the intended recipient or his/her representative you are not authorised to, and must not, read, copy, distribute, use or retain this message or any part of it.
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Thanks Federico. I don't know much about the topic myself, but I've asked around, and consensus does seem to be on removing the text, as it's probably now dated/incorrect. On Sun, May 12, 2024 at 6:02 PM Federico Razzoli via docs < docs@lists.mariadb.org> wrote:
I've just noticed this paragraph:
https://mariadb.com/kb/en/mariadb-memory-allocation/#hyperthreading-and-mult...
1)
"HyperThreading is great for marketing, lousy for performance. It involves having two processing units sharing a single hardware cache. If both units are doing the same thing, the cache will be reasonably useful. If the units are doing different things, they will be clobbering each other's cache entries."
I believe it is entirely based on a misconception: HTT has nothing to do with threads "doing the same thing".
2)
About the part that warns us from using too many cores: I believe it was correct some years ago, but not today, or at least not for just 8 cores.
*
I don't feel comfortable deleting what others wrote, so I'll just raise the problems here.
Federico
-- Federico Razzoli Vettabase Ltd director & founder, Database Consultant https://vettabase.com federico.razzoli@vettabase.com +44 7739 427279 Telegram: federico_razzoli Skype: fede.razzoli
The information in this e-mail and any attachments may be confidential. If you received it by mistake, please inform the sender. Unless you are the intended recipient or his/her representative you are not authorised to, and must not, read, copy, distribute, use or retain this message or any part of it. _______________________________________________ docs mailing list -- docs@lists.mariadb.org To unsubscribe send an email to docs-leave@lists.mariadb.org
participants (2)
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Federico Razzoli
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Ian Gilfillan