From: Blue Swirl <blauwirbel@gmail.com>
To: Richard Henderson <rth@twiddle.net>
Cc: aurelien@aurel32.net, qemu-devel@nongnu.org,
Nathan Froyd <froydnj@codesourcery.com>
Subject: Re: [Qemu-devel] [PATCH 09/10] target-alpha: Implement load-locked/store-conditional properly.
Date: Thu, 25 Mar 2010 19:40:30 +0200 [thread overview]
Message-ID: <f43fc5581003251040q1ebe12c3u124baf80c9a92cce@mail.gmail.com> (raw)
In-Reply-To: <4BAB853E.1070303@twiddle.net>
On 3/25/10, Richard Henderson <rth@twiddle.net> wrote:
> On 03/25/2010 06:39 AM, Nathan Froyd wrote:
> > On Wed, Mar 24, 2010 at 05:11:43PM -0700, Richard Henderson wrote:
> >> Use __sync_bool_compare_and_swap to yield correctly atomic results.
> >> As yet, this assumes running on an strict-memory-ordering host (i.e. x86),
> >> since we're still "implementing" the memory-barrier instructions as nops.
> >
> > Did the approach taken by other targets (arm/mips/ppc) not work on
> > Alpha?
>
>
> Mips doesn't even pretend to be atomic.
>
> Powerpc and Arm -- if I've got this straight -- use some sort of stop-the-world
> mutex+condition and then perform the compare-and-exchange by hand. I can't
> see how that's better than using an actual compare-and-exchange provided by
> the host cpu. In fact, I'm mildly horrified by the prospect.
>
> Honestly. Even ARM and HPPA which doesn't (always) natively have cmpxchg, have
> an easy to use kernel trap to perform the operation. I suppose real 80386 and
> sparc-pre-v9 don't have anything particularly useful, but frankly it wouldn't
> bother me to deprecate them as hosts since the modern editions all do work.
Sparc V8 has two atomic instructions, ldstub and swap.
next prev parent reply other threads:[~2010-03-25 17:40 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-25 0:24 [Qemu-devel] [PATCH 00/10, v3] target-alpha improvements Richard Henderson
2010-03-12 18:31 ` [Qemu-devel] [PATCH 01/10] target-alpha: Add flags markups to helpers.h Richard Henderson
2010-03-12 19:22 ` [Qemu-devel] [PATCH 02/10] target-alpha: Implement cpys{, n, e} inline Richard Henderson
2010-03-15 14:49 ` [Qemu-devel] [PATCH 03/10] target-alpha: Implement rs/rc properly Richard Henderson
2010-03-15 15:38 ` [Qemu-devel] [PATCH 05/10] target-alpha: Implement cvtlq inline Richard Henderson
2010-03-16 20:04 ` [Qemu-devel] [PATCH 06/10] target-alpha: Use setcond for int comparisons Richard Henderson
2010-03-16 21:44 ` [Qemu-devel] [PATCH 07/10] target-alpha: Use non-inverted arguments to gen_{f}cmov Richard Henderson
2010-03-16 22:10 ` [Qemu-devel] [PATCH 08/10] target-alpha: Emit goto_tb opcodes Richard Henderson
2010-03-19 22:55 ` [Qemu-devel] [PATCH 04/10] target-alpha: Implement cvtql inline Richard Henderson
2010-03-25 0:11 ` [Qemu-devel] [PATCH 09/10] target-alpha: Implement load-locked/store-conditional properly Richard Henderson
2010-03-25 13:39 ` Nathan Froyd
2010-03-25 15:46 ` Richard Henderson
2010-03-25 16:06 ` Nathan Froyd
2010-03-25 16:29 ` Richard Henderson
2010-03-25 16:42 ` Nathan Froyd
2010-03-25 16:50 ` Richard Henderson
2010-03-25 17:40 ` Blue Swirl [this message]
2010-03-25 18:19 ` Richard Henderson
2010-03-26 1:55 ` Jamie Lokier
2010-03-26 2:01 ` Jamie Lokier
2010-03-25 0:13 ` [Qemu-devel] [PATCH 10/10] target-alpha: Enable NPTL Richard Henderson
2010-03-26 1:52 ` [Qemu-devel] [PATCH 00/10, v3] target-alpha improvements Jamie Lokier
2010-03-26 13:37 ` Richard Henderson
2010-04-01 13:44 ` Paul Brook
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