From: george anzinger <george@mvista.com>
To: "David S. Miller" <davem@redhat.com>
Cc: Keith Owens <kaos@ocs.com.au>,
nigel@nrg.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH for 2.5] preemptible kernel
Date: Wed, 21 Mar 2001 02:57:45 -0800 [thread overview]
Message-ID: <3AB88929.D1B324F2@mvista.com> (raw)
In-Reply-To: <Pine.LNX.4.05.10103201920410.26853-100000@cosmic.nrg.org> <22991.985166394@ocs3.ocs-net> <15032.30533.638717.696704@pizda.ninka.net>
"David S. Miller" wrote:
>
> Keith Owens writes:
> > Or have I missed something?
>
> Nope, it is a fundamental problem with such kernel pre-emption
> schemes. As a result, it would also break our big-reader locks
> (see include/linux/brlock.h).
He has this one covered. The patch puts preemption locks around
read_locks.
By the by, if a preemption lock is all that is needed the patch defines
it and it is rather fast (an inc going in and a dec & test comming
out). A lot faster than a spin lock with its "LOCK" access. A preempt
lock does not need to be "LOCK"ed because the only contender is the same
cpu.
George
>
> Basically, anything which uses smp_processor_id() would need to
> be holding some lock so as to not get pre-empted.
>
> Later,
> David S. Miller
> davem@redhat.com
next prev parent reply other threads:[~2001-03-21 11:03 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-03-15 1:25 [PATCH for 2.5] preemptible kernel Nigel Gamble
2001-03-17 17:34 ` Pavel Machek
2001-03-19 21:01 ` Nigel Gamble
2001-03-20 8:43 ` Rusty Russell
2001-03-20 9:32 ` Keith Owens
2001-03-21 0:48 ` Nigel Gamble
2001-03-21 1:23 ` Keith Owens
2001-03-21 3:35 ` Nigel Gamble
2001-03-21 8:04 ` george anzinger
2001-03-21 9:04 ` Keith Owens
2001-03-21 14:32 ` Rusty Russell
2001-03-23 20:42 ` Nigel Gamble
2001-03-28 11:47 ` Dipankar Sarma
2001-03-21 9:19 ` Keith Owens
2001-03-21 9:41 ` David S. Miller
2001-03-21 10:05 ` Andrew Morton
2001-03-22 0:20 ` Nigel Gamble
2001-03-21 10:57 ` george anzinger [this message]
2001-03-21 11:30 ` David S. Miller
2001-03-21 17:07 ` george anzinger
2001-03-21 18:18 ` Nigel Gamble
2001-03-21 22:25 ` Rusty Russell
2001-03-21 15:46 ` Andrea Arcangeli
2001-03-28 10:20 ` Dipankar Sarma
2001-03-28 20:51 ` george anzinger
2001-03-29 9:43 ` Dipankar Sarma
2001-03-30 6:32 ` Keith Owens
2001-03-21 0:24 ` Nigel Gamble
2001-03-30 0:26 ` Nigel Gamble
2001-03-30 20:11 ` Rusty Russell
2001-04-01 7:48 ` george anzinger
2001-04-01 21:13 ` Nigel Gamble
2001-04-02 19:56 ` george anzinger
2001-04-04 17:59 ` Rusty Russell
2001-04-01 21:07 ` Nigel Gamble
2001-04-04 17:51 ` Rusty Russell
2001-03-20 18:25 ` Roger Larsson
2001-03-20 22:06 ` Nigel Gamble
2001-03-20 22:27 ` george anzinger
-- strict thread matches above, loose matches on Subject: below --
2001-04-06 23:52 Paul McKenney
2001-04-07 0:45 ` Andi Kleen
2001-04-07 1:25 Paul McKenney
2001-04-07 19:59 ` Rusty Russell
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