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Re: [Qemu-devel] [PATCH 1/2] exec: do not use qemu/tls.h
From: |
Andreas Färber |
Subject: |
Re: [Qemu-devel] [PATCH 1/2] exec: do not use qemu/tls.h |
Date: |
Mon, 01 Jul 2013 12:47:39 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 |
Am 01.07.2013 11:35, schrieb Stefan Hajnoczi:
> From: Paolo Bonzini <address@hidden>
>
> The next patch will change qemu/tls.h to support more platforms, but at
> some performance cost. Declare cpu_single_env directly instead of using
> the tls.h abstractions.
>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
> exec.c | 10 ++++++++--
> include/exec/cpu-all.h | 14 +++++++++++---
> include/qemu/tls.h | 52
> --------------------------------------------------
> 3 files changed, 19 insertions(+), 57 deletions(-)
> delete mode 100644 include/qemu/tls.h
>
> diff --git a/exec.c b/exec.c
> index c49806c..02263db 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -70,9 +70,15 @@ static MemoryRegion io_mem_unassigned;
> #endif
>
> CPUArchState *first_cpu;
> +
> /* current CPU in the current thread. It is only valid inside
> - cpu_exec() */
> -DEFINE_TLS(CPUArchState *,cpu_single_env);
> + * cpu_exec(). See comment in include/exec/cpu-all.h. */
> +#if defined CONFIG_KVM || (defined CONFIG_USER_ONLY && defined
> CONFIG_USE_NPTL)
> +__thread CPUArchState *cpu_single_env;
> +#else
> +CPUArchState *cpu_single_env;
> +#endif
As indicated elsewhere, this conflicts with my pending CPUState part 10
series, which moves, renames and changes type of cpu_single_env:
http://patchwork.ozlabs.org/patch/254825/
The latest version received no further feedback after finding a better
name than cpu_single_cpu (current_cpu), first_cpu/next_cpu is ack'ed and
so are the prereqs for current_cpu, so I will pull that in as soon as
potential conflicts with ppc and memory pulls are sorted out, since
pretty invasive and a milestone towards getting rid of CPUArchState.
I'd be happy to help with rebasing this afterwards when needed.
Regards,
Andreas
> +
> /* 0 = Do not count executed instructions.
> 1 = Precise instruction counting.
> 2 = Adaptive rate instruction counting. */
> diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
> index 35bdf85..7e8df70 100644
> --- a/include/exec/cpu-all.h
> +++ b/include/exec/cpu-all.h
> @@ -20,7 +20,6 @@
> #define CPU_ALL_H
>
> #include "qemu-common.h"
> -#include "qemu/tls.h"
> #include "exec/cpu-common.h"
> #include "qemu/thread.h"
>
> @@ -358,8 +357,17 @@ CPUArchState *cpu_copy(CPUArchState *env);
> void QEMU_NORETURN cpu_abort(CPUArchState *env, const char *fmt, ...)
> GCC_FMT_ATTR(2, 3);
> extern CPUArchState *first_cpu;
> -DECLARE_TLS(CPUArchState *,cpu_single_env);
> -#define cpu_single_env tls_var(cpu_single_env)
> +
> +/* This is thread-local depending on __linux__ because:
> + * - the only -user mode supporting multiple VCPU threads is linux-user
> + * - TCG system mode is single-threaded regarding VCPUs
> + * - KVM system mode is multi-threaded but limited to Linux
> + */
> +#if defined CONFIG_KVM || (defined CONFIG_USER_ONLY && defined
> CONFIG_USE_NPTL)
> +extern __thread CPUArchState *cpu_single_env;
> +#else
> +extern CPUArchState *cpu_single_env;
> +#endif
>
> /* Flags for use in ENV->INTERRUPT_PENDING.
>
> diff --git a/include/qemu/tls.h b/include/qemu/tls.h
> deleted file mode 100644
> index b92ea9d..0000000
> --- a/include/qemu/tls.h
> +++ /dev/null
> @@ -1,52 +0,0 @@
> -/*
> - * Abstraction layer for defining and using TLS variables
> - *
> - * Copyright (c) 2011 Red Hat, Inc
> - * Copyright (c) 2011 Linaro Limited
> - *
> - * Authors:
> - * Paolo Bonzini <address@hidden>
> - * Peter Maydell <address@hidden>
> - *
> - * This program is free software; you can redistribute it and/or
> - * modify it under the terms of the GNU General Public License as
> - * published by the Free Software Foundation; either version 2 of
> - * the License, or (at your option) any later version.
> - *
> - * This program is distributed in the hope that it will be useful,
> - * but WITHOUT ANY WARRANTY; without even the implied warranty of
> - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> - * GNU General Public License for more details.
> - *
> - * You should have received a copy of the GNU General Public License along
> - * with this program; if not, see <http://www.gnu.org/licenses/>.
> - */
> -
> -#ifndef QEMU_TLS_H
> -#define QEMU_TLS_H
> -
> -/* Per-thread variables. Note that we only have implementations
> - * which are really thread-local on Linux; the dummy implementations
> - * define plain global variables.
> - *
> - * This means that for the moment use should be restricted to
> - * per-VCPU variables, which are OK because:
> - * - the only -user mode supporting multiple VCPU threads is linux-user
> - * - TCG system mode is single-threaded regarding VCPUs
> - * - KVM system mode is multi-threaded but limited to Linux
> - *
> - * TODO: proper implementations via Win32 .tls sections and
> - * POSIX pthread_getspecific.
> - */
> -#ifdef __linux__
> -#define DECLARE_TLS(type, x) extern DEFINE_TLS(type, x)
> -#define DEFINE_TLS(type, x) __thread __typeof__(type) tls__##x
> -#define tls_var(x) tls__##x
> -#else
> -/* Dummy implementations which define plain global variables */
> -#define DECLARE_TLS(type, x) extern DEFINE_TLS(type, x)
> -#define DEFINE_TLS(type, x) __typeof__(type) tls__##x
> -#define tls_var(x) tls__##x
> -#endif
> -
> -#endif
>
--
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[Qemu-devel] [PATCH 1/2] exec: do not use qemu/tls.h, Stefan Hajnoczi, 2013/07/01