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Date:      Tue, 21 May 2013 04:56:20 +0000
From:      Orit Moskovich <oritm@mellanox.com>
To:        "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org>
Subject:   compatibility layer - workqueues
Message-ID:  <981733489AB3BD4DB24B48340F53E0A55B0D0938@MTLDAG01.mtl.com>

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Hi,

I'm working on understanding the difference between Linux and FreeBSD inter=
rupt handling.
I looked at the compatibility layer and noticed this:


*         Linux workqueues are implemented using FreeBSD taskqueues (under =
sys/ofed/include/linux/workqueue.h)

*         In linux, the function schedule_work() puts a job in the kernel g=
lobal workqueue 'events'. This workqueue consists of worker threads - one p=
er processor

*         The compatibility layer wraps this function to a macro, that impl=
ements the functionality using taskqueue_enqueue() and set it to work on ta=
skqueue_thread, that executes its tasks in the context of a kernel thread

*         BUT,  taskqueue_thread is initialized in:

o   sys/kern/subr_taskqueue.c  line 536:
TASKQUEUE_DEFINE_THREAD(thread);

o   which is defined in sys/taskqueue.h line 133
and run taskqueue_start_threads() with only 1 thread, and not MAXCPU



I'll appreciate your help understanding this issue,



Thanks,

Orit Moskovich





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