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Date:      Wed, 22 Mar 2000 12:53:07 -0800
From:      Greg Lehey <grog@lemis.com>
To:        Poul-Henning Kamp <phk@critter.freebsd.dk>
Cc:        Wes Peters <wes@softweyr.com>, Warner Losh <imp@village.org>, hackers@FreeBSD.ORG
Subject:   Re: splFoo() question
Message-ID:  <20000322125307.B2183@mojave.worldwide.lemis.com>
In-Reply-To: <23423.953621217@critter.freebsd.dk>; from phk@critter.freebsd.dk on Tue, Mar 21, 2000 at 07:46:57AM %2B0100
References:  <38D6B353.FA58BB15@softweyr.com> <23423.953621217@critter.freebsd.dk>

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On Tuesday, 21 March 2000 at  7:46:57 +0100, Poul-Henning Kamp wrote:
> In message <38D6B353.FA58BB15@softweyr.com>, Wes Peters writes:
>> Poul-Henning Kamp wrote:
>>>
>>> In message <200003182031.NAA97975@harmony.village.org>, Warner Losh writes:
>>>
>>>> I'd like to be able to do some simple spl locking in a driver that I'm
>>>> writing.  While I could go the splhigh() route, I'm concerned that
>>>> spending lots of time at splhigh could cause problems, and some of my
>>>> critical sections look to be very expensive.  They only need
>>>> protection against the card itself, not against the entire system.  It
>>>> just seems to be an overly large hammer.
>>>
>>> I miss this too.
>>
>> Semaphores?
>
> spl*() are semaphores.

spl*() are interrupt lockouts.  The difference is very evident in an
SMP environment.

Greg
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