From: "Emilio G. Cota" <cota@braap.org>
To: Richard Henderson <rth@twiddle.net>
Cc: "QEMU Developers" <qemu-devel@nongnu.org>,
"MTTCG Devel" <mttcg@greensocs.com>,
"Alex Bennée" <alex.bennee@linaro.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Peter Crosthwaite" <crosthwaite.peter@gmail.com>,
"Peter Maydell" <peter.maydell@linaro.org>,
"Sergey Fedorov" <serge.fdrv@gmail.com>
Subject: Re: [Qemu-devel] [PATCH v3 05/11] qemu-thread: add simple test-and-set spinlock
Date: Wed, 20 Apr 2016 14:11:32 -0400 [thread overview]
Message-ID: <20160420181132.GA24862@flamenco> (raw)
In-Reply-To: <5717C2A1.9010805@twiddle.net>
On Wed, Apr 20, 2016 at 10:55:45 -0700, Richard Henderson wrote:
> On 04/20/2016 10:17 AM, Emilio G. Cota wrote:
> >I've tried to find a GCC intrinsic for test-and-set, and I've only found
> >lock_test_and_set, which is what we use for atomic_xchg (except on ppc)
> >because it really is an atomic exchange:
> > "This builtin, as described by Intel, is not a traditional test-and-set
> > operation, but rather an atomic exchange operation."
> > https://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Atomic-Builtins.html
>
> Please read the entire documentation, not just the first sentence.
I did read it and I'm aware of the limitations of using xchg.
My comment was related to this:
> [...] do note that there are compiler primitives for test-and-set that
> (can be) simpler for a cpu to implement than xchg.
What compiler (I assume gcc) primitives are these? I couldn't find them.
Thanks,
Emilio
next prev parent reply other threads:[~2016-04-20 18:11 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-19 23:07 [Qemu-devel] [PATCH v3 00/11] tb hash improvements Emilio G. Cota
2016-04-19 23:07 ` [Qemu-devel] [PATCH v3 01/11] compiler.h: add QEMU_ALIGNED() to enforce struct alignment Emilio G. Cota
2016-04-22 9:32 ` Alex Bennée
2016-04-22 9:35 ` Peter Maydell
2016-04-22 15:50 ` Emilio G. Cota
2016-04-19 23:07 ` [Qemu-devel] [PATCH v3 02/11] seqlock: remove optional mutex Emilio G. Cota
2016-04-19 23:07 ` [Qemu-devel] [PATCH v3 03/11] seqlock: rename write_lock/unlock to write_begin/end Emilio G. Cota
2016-04-19 23:07 ` [Qemu-devel] [PATCH v3 04/11] include/processor.h: define cpu_relax() Emilio G. Cota
2016-04-20 12:15 ` KONRAD Frederic
2016-04-20 17:16 ` Emilio G. Cota
2016-04-20 17:18 ` Peter Maydell
2016-04-20 17:32 ` [Qemu-devel] [UPDATED " Emilio G. Cota
2016-04-22 9:35 ` [Qemu-devel] [PATCH " Alex Bennée
2016-04-19 23:07 ` [Qemu-devel] [PATCH v3 05/11] qemu-thread: add simple test-and-set spinlock Emilio G. Cota
2016-04-20 15:18 ` Richard Henderson
2016-04-20 17:17 ` Emilio G. Cota
2016-04-20 17:55 ` Richard Henderson
2016-04-20 18:11 ` Emilio G. Cota [this message]
2016-04-20 19:39 ` Richard Henderson
2016-04-21 16:24 ` Emilio G. Cota
2016-04-20 17:35 ` [Qemu-devel] [UPDATED " Emilio G. Cota
2016-04-19 23:07 ` [Qemu-devel] [PATCH v3 06/11] exec: add tb_hash_func5, derived from xxhash Emilio G. Cota
2016-04-20 15:19 ` Richard Henderson
2016-04-22 12:58 ` Alex Bennée
2016-04-19 23:07 ` [Qemu-devel] [PATCH v3 07/11] tb hash: hash phys_pc, pc, and flags with xxhash Emilio G. Cota
2016-04-22 12:58 ` Alex Bennée
2016-04-19 23:07 ` [Qemu-devel] [PATCH v3 08/11] qht: QEMU's fast, resizable and scalable Hash Table Emilio G. Cota
2016-04-22 14:04 ` Alex Bennée
2016-04-24 20:01 ` Richard Henderson
2016-04-24 21:58 ` Emilio G. Cota
2016-04-19 23:07 ` [Qemu-devel] [PATCH v3 09/11] qht: add test program Emilio G. Cota
2016-04-22 14:35 ` Alex Bennée
2016-04-19 23:07 ` [Qemu-devel] [PATCH v3 10/11] tb hash: track translated blocks with qht Emilio G. Cota
2016-04-28 13:27 ` Alex Bennée
2016-04-19 23:07 ` [Qemu-devel] [PATCH v3 11/11] translate-all: add tb hash bucket info to 'info jit' dump Emilio G. Cota
2016-04-20 15:21 ` Richard Henderson
2016-04-22 14:38 ` Alex Bennée
2016-04-22 17:41 ` Richard Henderson
2016-04-22 19:23 ` Emilio G. Cota
2016-04-22 19:59 ` Richard Henderson
2016-04-22 23:57 ` Emilio G. Cota
2016-04-24 19:46 ` Richard Henderson
2016-04-24 22:06 ` Emilio G. Cota
2016-04-27 2:43 ` Emilio G. Cota
2016-04-28 16:37 ` Richard Henderson
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