No subject

Yuxin Ren ryx at
Fri Apr 24 18:26:56 CEST 2015

I think a thread maybe migrated to another core due to contention of
helping lock.
But what do you mean by "some extra work will need to be done in the
"schedule" function"?
What is "extra work" and "special context"?


On Thu, Apr 23, 2015 at 8:52 PM, <deng.chao1 at> wrote:

> Hi:
>     I am reading the code of fiasco kernel.I have a question about the
> function "Context::schedule".
>     At line 894 in kernel/fiasco/src/kern/context.cpp:
>         "while (EXPECT_FALSE(current_cpu != access_once(&_home_cpu)))"
>     As I know, the variable "_home_cpu" indicates the CPU number which the
> thread that invokes the “schedue ” as a member function is running on。And
> the variable “current cpu” indicates the CPU number now this code fragment
> is running on。
>     The condition test tells me that it seems the class Context's member
> function "schedule" will run on a different cpu some time . If it does so,
> some extra work will need to be done in the "schedule" function. I have
> searched all of the fiasco kernel sources, but  I did not find this special
> context.
>     So would anybody please tell me whether there has a situation that the
> "schedule"  function will run on different CPU, why does it happen?
> Thanks!
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