{"id":28784,"date":"2020-04-23T15:12:42","date_gmt":"2020-04-23T19:12:42","guid":{"rendered":"https:\/\/mjtsai.com\/blog\/?p=28784"},"modified":"2020-06-05T16:03:31","modified_gmt":"2020-06-05T20:03:31","slug":"throttling-due-to-thunderbolt-left-proximity-sensor","status":"publish","type":"post","link":"https:\/\/mjtsai.com\/blog\/2020\/04\/23\/throttling-due-to-thunderbolt-left-proximity-sensor\/","title":{"rendered":"Throttling Due to Thunderbolt Left Proximity Sensor"},"content":{"rendered":"

Dion Almaer<\/a>:<\/p>\n

\n

Do you charge your Macbook on the left or right side? Turns out right is better!<\/p>\n<\/blockquote>\n

Adam<\/a>:<\/p>\n

Occasionally my machine will have a kernel_task<\/code> instance max out the CPU[…] This can last from minutes to sometimes hours. The machine is effectively unusable in this state. Restarting doesn’t help; a new kernel_task<\/code> pops up again until it finishes whatever it’s doing.<\/p>\n

[…]<\/p>\n

State C shows that simply having stuff plugged in to TB ports raises their temperature significantly. Both the hub (mouse and keyboard ONLY) and HDMI adapter individually raise the temperature about 10 degrees, and 15 degrees together.<\/p>\n

Note that high temperature on the right side appears to be ignored by the OS. Plugging everything into the two right ports instead of the left raised the Right temperatures to over 100 degrees, without the fans coming on. No kernel_task<\/code> either, but the machine becomes unusable from something<\/em> throttling.<\/p><\/blockquote>\n\n

Joseph Pierini<\/a>:<\/p>\n

\n

Just had this problem on Catalina 10.15.4.<\/p>\n<\/blockquote>\n\n

Again, it seems like Apple’s notebooks aren’t designed with enough thermal headroom.<\/p>\n\n

Update (2020-04-23): See also: Hacker<\/a> News<\/a>, Igor Kromin<\/a>.<\/p>\n\n

Update (2020-04-24): Peter Steinberger<\/a>:<\/p>\n

\n

This finally explains what high kernel_task is, and why it happens. I spent so much time on it; wrote radars, escalated to Apple support; replaced hardware (!) to finally see that it’s temperature emergency code because I plugged in the LG 5k monitor left.<\/p>\n

It’s maddening. Probably a design compromise [so] it can be 1mm thinner.<\/p>\n

It changed the way I work - almost stopped using external screens because of this bug. The back pain this caused...<\/p>\n<\/blockquote>\n\n

Update (2020-06-05): Apple<\/a> (via Lloyd Chambers<\/a>):<\/p>\n

One of the functions of kernel_task is to help manage CPU temperature by making the CPU less available to processes that are using it intensely. In other words, kernel_task responds to conditions that cause your CPU to become too hot, even if your Mac doesn’t feel hot to you. It does not itself cause those conditions. When the CPU temperature decreases, kernel_task automatically reduces its activity.<\/p><\/blockquote>\n\n

See also: Howard Oakley<\/a>.<\/p>","protected":false},"excerpt":{"rendered":"

Dion Almaer: Do you charge your Macbook on the left or right side? Turns out right is better! Adam: Occasionally my machine will have a kernel_task instance max out the CPU[…] This can last from minutes to sometimes hours. The machine is effectively unusable in this state. Restarting doesn’t help; a new kernel_task pops up […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"apple_news_api_created_at":"2020-04-23T19:12:45Z","apple_news_api_id":"3e6f56e7-9f8d-4611-8199-7cf9d8fbdef5","apple_news_api_modified_at":"2020-06-05T20:03:35Z","apple_news_api_revision":"AAAAAAAAAAAAAAAAAAAABg==","apple_news_api_share_url":"https:\/\/apple.news\/APm9W55-NRhGBmXz52Pve9Q","apple_news_coverimage":0,"apple_news_coverimage_caption":"","apple_news_is_hidden":false,"apple_news_is_paid":false,"apple_news_is_preview":false,"apple_news_is_sponsored":false,"apple_news_maturity_rating":"","apple_news_metadata":"\"\"","apple_news_pullquote":"","apple_news_pullquote_position":"","apple_news_slug":"","apple_news_sections":"\"\"","apple_news_suppress_video_url":false,"apple_news_use_image_component":false,"footnotes":""},"categories":[2],"tags":[1581,30,100,1609,1666,280,1942,201,1154],"class_list":["post-28784","post","type-post","status-publish","format-standard","hentry","category-technology","tag-istat-menus","tag-mac","tag-macbookpro","tag-macos-10-14","tag-macos-10-15","tag-power","tag-thermal","tag-thunderbolt","tag-usb-c"],"apple_news_notices":[],"_links":{"self":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/28784","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/comments?post=28784"}],"version-history":[{"count":7,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/28784\/revisions"}],"predecessor-version":[{"id":29172,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/28784\/revisions\/29172"}],"wp:attachment":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/media?parent=28784"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/categories?post=28784"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/tags?post=28784"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}