Messages in this thread | | | Subject | Re: [RFC PATCH v2 11/17] sched: Basic tracking of matching tasks | From | Subhra Mazumdar <> | Date | Wed, 8 May 2019 11:19:46 -0700 |
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On 5/8/19 8:49 AM, Aubrey Li wrote: >> Pawan ran an experiment setting up 2 VMs, with one VM doing a parallel kernel build and one VM doing sysbench, >> limiting both VMs to run on 16 cpu threads (8 physical cores), with 8 vcpu for each VM. >> Making the fix did improve kernel build time by 7%. > I'm gonna agree with the patch below, but just wonder if the testing > result is consistent, > as I didn't see any improvement in my testing environment. > > IIUC, from the code behavior, especially for 2 VMs case(only 2 > different cookies), the > per-rq rb tree unlikely has nodes with different cookies, that is, all > the nodes on this > tree should have the same cookie, so: > - if the parameter cookie is equal to the rb tree cookie, we meet a > match and go the > third branch > - else, no matter we go left or right, we can't find a match, and > we'll return idle thread > finally. > > Please correct me if I was wrong. > > Thanks, > -Aubrey This is searching in the per core rb tree (rq->core_tree) which can have 2 different cookies. But having said that, even I didn't see any improvement with the patch for my DB test case. But logically it is correct.
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