Date: Thu, 15 Jan 2009 14:19:09 -0800 From: Pramod Srinivasan <pramod@juniper.net> To: Daniel Eischen <deischen@freebsd.org> Cc: freebsd-threads@freebsd.org Subject: Re: Priority scheduling in 6.x Message-ID: <C594F65D.5677C%pramod@juniper.net> In-Reply-To: <Pine.GSO.4.64.0901142220230.27761@sea.ntplx.net>
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Hi Daniel
Thanks for your response.
On 1/14/09 7:25 PM, "Daniel Eischen" <deischen@freebsd.org> wrote:
> On Wed, 14 Jan 2009, Pramod Srinivasan wrote:
>
>> Hi,
>>
>> I have 3 threads low, medium and high , and the scheduling policy is set to
>> SCHED_FIFO. The priority of the threads are at 28,29,30 respectively. Looks
>> like on FreeBSD 6.x, the priority of the threads are not honored while
>> scheduling the threads, but the same test on FreeBSD 7.x seems to work fine.
>> Are there known issues with the priority scheduling in FreeBSD 6.x or am I
>> doing something wrong? (I am using libthr)
>
> Are you using libpthread or libthr on 6.3?
I am using libthr on 6.1, but had similar issues on 6.2 as well.
>
> If you are using libthr, then you need to be running with
> superuser privileges for SCHED_FIFO to work. I'm not sure
> if this works correctly at all in 6.3.
I am running the program with super user privileges on 6.1, tried this on
6.2 as well. Priority scheduling using libthr does not work, unless I am
missing something very basic?. The same program works fine on 7.1, any
ideas?
>
> If you are using libpthread, then it will work if the
> threads are PTHREAD_SCOPE_PROCESS, but will not work
> if they are PTHREAD_SCOPE_SYSTEM. You do not need
> superuser privileges for SCHED_FIFO with libpthread
> and process scope threads. I don't believe the kernel
> has ever worked properly for libpthread (kse) SCHED_FIFO
> system scope threads.
I tried libpthread with PTHREAD_SCOPE_PROCESS, it was better, I see that the
priority is honored. Thanks for the pointer.
Thanks,
Pramod
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