Date: Wed, 17 Sep 2014 21:38:19 +0400 From: Andrey Chernov <ache@freebsd.org> To: Alexander Motin <mav@FreeBSD.org>, Alan Cox <alc@rice.edu>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: Re: svn commit: r271707 - stable/10/sys/kern Message-ID: <5419C70B.4010209@freebsd.org> In-Reply-To: <5419C67F.90808@FreeBSD.org> References: <201409171406.s8HE6LNu071461@svn.freebsd.org> <5419B3E1.1090703@freebsd.org> <5419BAD7.4000600@FreeBSD.org> <5419BFF9.9080907@rice.edu> <5419C67F.90808@FreeBSD.org>
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On 17.09.2014 21:35, Alexander Motin wrote:
> On 17.09.2014 20:08, Alan Cox wrote:
>> On 09/17/2014 11:46, Alexander Motin wrote:
>>> On 17.09.2014 19:16, Andrey Chernov wrote:
>>>> On 17.09.2014 18:06, Alexander Motin wrote:
>>>>> + /*
>>>>> + * Make sure that tdq_load updated before calling this function
>>>>> + * is globally visible before we read tdq_cpu_idle. Idle thread
>>>>> + * accesses both of them without locks, and the order is important.
>>>>> + */
>>>>> + mb();
>>>>> +
>>>>> if (TD_IS_IDLETHREAD(ctd)) {
>>>> I don't understand this comment's first phrase with two verbs. Copy &
>>>> paste result?
>>> No, only possibly missing commas around "updated before calling this
>>> function".
>>
>>
>> Commas alone don't fix the problem. I think what you're trying to say is:
>>
>> "Make sure that our caller's earlier update to tdq_load is globally
>> visible before we read tdq_cpu_idle."
>
> Yes, that was my intention. Thank you. Please excuse my non-native
> English and correct it as you feel better.
>
> Andrey, would that reveal your questions?
Sound nice for me, commit, please.
>
>>>> I also don't see tdq_load access in this function.
>>> It is incremented by tdq_load_add(), called by tdq_add(), called by
>>> sched_add(), just before calling tdq_notify().
>
--
http://ache.vniz.net/
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