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Date: Mon, 4 Mar 2002 12:13:50 -0800 (PST)
From: Davide Libenzi <davidel@xmailserver.org>
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To: Robert Love <rml@tech9.net>
cc: Rusty Russell <rusty@rustcorp.com.au>,
        Linus Torvalds <torvalds@transmeta.com>, <matthew@hairy.beasts.org>,
        Benjamin LaHaise <bcrl@redhat.com>, <david@mysql.com>,
        <wli@holomorphy.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Hubertus Franke <frankeh@watson.ibm.com>
Subject: Re: [PATCH] Fast Userspace Mutexes III.
In-Reply-To: <1015271393.15277.112.camel@phantasy>
Message-ID: <Pine.LNX.4.44.0203041208310.1561-100000@blue1.dev.mcafeelabs.com>
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On 4 Mar 2002, Robert Love wrote:

> On Sun, 2002-03-03 at 22:55, Rusty Russell wrote:
> > 1) Use mmap/mprotect bits, not new syscall (thanks RTH, Erik Biederman)
> > 2) Fix wakeup race in kernel (thanks Martin Wirth, Paul Mackerras)
> > 3) Simplify locking to a single atomic (no more arch specifics!)
> > 4) Use wake-one by handcoding queues.
> > 5) Comments added.
> >
> > Thanks to all for feedback and review: I'd appreciate a comment from
> > those arch's which need to do something with the PROT_SEM bit.
> >
> > Once again, tested on 2.4.18 UP PPC, compiles on 2.5.6-pre1.
> >
> > Bad news is that we're up to 206 lines again.
> > Rusty.
>
> Good work.  I likee.

Ok, i reply to this because my 'd' Pine's key is heavily used in these days :-)
I took a look at the code yesterday night and i've a stupid question
Rusty. I do not know what is the code used in the upper part of the
iceberg ( userspace ) but are you doing a dec_and_test() on userspace
before entering the kernel ? Or, is the kernel code the slow path or you
enter it by default ?



- Davide


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