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From:   "Alex Zhu (Kernel)" <alexlzhu@fb.com>
To:     William Kucharski <william.kucharski@oracle.com>
CC:     "linux-mm@kvack.org" <linux-mm@kvack.org>,
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Subject: Re: [PATCH v3] mm: add thp_utilization metrics to
 /proc/thp_utilization
Thread-Topic: [PATCH v3] mm: add thp_utilization metrics to
 /proc/thp_utilization
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Date:   Fri, 5 Aug 2022 21:46:42 +0000
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> 
> Out of curiosity, do you have any statistics on how much of a performance impact scanning may have?
> 
> We've reached the point where we've finally been able to show previous admonitions to not enable THP due to a negative performance impact no longer hold true, and I'd hate to see systems on which enabling THP now would cause a performance hit due to this scanner.

There are no noticeable performance issues from running the scanner itself from our experiments. As written, we check 256 pfn s at a time every second, which does not appear to be an issue.