Re: Understanding hard CPU limits
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Marco Voelz
/cc Eric and Julz: Could you maybe help us understand this? Thanks! From: cf-dev@... <cf-dev@...> on behalf of Grifalconi, Michael <michael.grifalconi@...>
Sent: Monday, March 26, 2018 10:54:32 AM To: cf-dev@... Subject: [CAUTION] [cf-dev] Understanding hard CPU limits Hi,
We were trying out the hard CPU limit as per docs https://github.com/cloudfoundry/garden-runc-release/releases?after=v1.9.2
according to formula for single core machine, APP_MEM_IN_MB * 100us / 1000 = MILLISECONDS_PER_100_MILLISECOND_PERIOD In our tests, to get 6.4% CPU usage on a 64MB application and ~100% for a 1GB application we had to set the 'cpu_quota_per_share_in_us' to 3200. (Cell has 4 core and 16GB or ram, overcommit factor of 2). That changes the formula to: APP_MEM_IN_MB * 100us / 32000 = MILLISECONDS_PER_100_MILLISECOND_PERIOD Can you help us to understand from where this 'times 32' comes from? Is the total available RAM of the cell (16GB * overcommit of 2) and number of cpu cores does not matter? Thanks and regards, Michael |
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