From: Richard Henderson <rth@twiddle.net>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: torvalds@transmeta.com, matthew@hairy.beasts.org,
bcrl@redhat.com, david@mysql.com, wli@holomorphy.com,
linux-kernel@vger.kernel.org, frankeh@watson.ibm.com
Subject: Re: [PATCH] Fast Userspace Mutexes III.
Date: Thu, 7 Mar 2002 00:48:21 -0800 [thread overview]
Message-ID: <20020307004821.A26624@twiddle.net> (raw)
In-Reply-To: <E16hjZY-0001AV-00@wagner.rustcorp.com.au> <20020306175203.A26064@twiddle.net> <20020307143947.000f51dd.rusty@rustcorp.com.au>
In-Reply-To: <20020307143947.000f51dd.rusty@rustcorp.com.au>; from rusty@rustcorp.com.au on Thu, Mar 07, 2002 at 02:39:47PM +1100
On Thu, Mar 07, 2002 at 02:39:47PM +1100, Rusty Russell wrote:
> But since the real problem here is "lock held forever", so I don't care.
No, "lock held forever" merely makes the example trivial.
"Lock held for a while" is the real problem.
> > You really do need that cmpxchg loop.
>
> Well, not decrementing if count < 0 already also works
How, exactly, are you planning on doing that atomically?
Clue: 386 SMP requires an extra spinlock.
> PS. Will Alpha have to do any special magic with the mmap PROT_SEM flag?
No.
r~
next prev parent reply other threads:[~2002-03-07 8:48 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-03-04 3:55 [PATCH] Fast Userspace Mutexes III Rusty Russell
2002-03-04 19:49 ` Robert Love
2002-03-04 20:13 ` Davide Libenzi
2002-03-04 20:20 ` Matthew Kirkwood
2002-03-04 20:48 ` Hubertus Franke
2002-03-04 22:15 ` Davide Libenzi
2002-03-05 1:50 ` Robert Love
2002-03-05 2:53 ` Davide Libenzi
2002-03-05 3:45 ` Rusty Russell
2002-03-05 3:55 ` Davide Libenzi
2002-03-05 6:11 ` Rusty Russell
2002-03-05 17:23 ` Davide Libenzi
2002-03-05 15:09 ` Hubertus Franke
2002-03-05 4:30 ` Edgar Toernig
2002-03-07 1:58 ` Richard Henderson
2002-03-07 2:10 ` Davide Libenzi
2002-03-05 4:48 ` Rusty Russell
2002-03-05 15:15 ` Hubertus Franke
2002-03-06 1:31 ` Rusty Russell
2002-03-05 1:34 ` Rusty Russell
2002-03-07 1:52 ` Richard Henderson
2002-03-07 3:39 ` Rusty Russell
2002-03-07 8:48 ` Richard Henderson [this message]
2002-03-07 9:17 ` Rusty Russell
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