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From: Richard Henderson <rth@twiddle.net>
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Date: Tue, 25 Apr 2017 13:01:48 +0200
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Subject: Re: [Qemu-devel] [PATCH v2 03/13] tcg: enforce 64-byte alignment of
 TCGContext
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To: "Emilio G. Cota" <cota@braap.org>, qemu-devel@nongnu.org
Cc: Paolo Bonzini <pbonzini@redhat.com>, Peter Crosthwaite <crosthwaite.peter@gmail.com>, Peter Maydell <peter.maydell@linaro.org>, Eduardo Habkost <ehabkost@redhat.com>, Andrzej Zaborowski <balrogg@gmail.com>, Aurelien Jarno <aurelien@aurel32.net>, Alexander Graf <agraf@suse.de>, Stefan Weil <sw@weilnetz.de>, qemu-arm@nongnu.org, alex.bennee@linaro.org, Pranith Kumar <bobby.prani+qemu@gmail.com>

On 04/25/2017 09:53 AM, Emilio G. Cota wrote:
> This will allow us to prevent cache line false sharing in TCGContext.
> 
> Before:
> $ objdump -t  build/x86_64-linux-user/qemu-x86_64 | grep tcg_ctx
> 00000000003ea820 g     O .bss   00000000000152d8              tcg_ctx
> 
> After:
> $ objdump -t  build/x86_64-linux-user/qemu-x86_64 | grep tcg_ctx
> 00000000003ea880 g     O .bss   0000000000015300              tcg_ctx
> 
> Signed-off-by: Emilio G. Cota <cota@braap.org>
> ---
>   tcg/tcg.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tcg/tcg.h b/tcg/tcg.h
> index 6c216bb..5fdbfe3 100644
> --- a/tcg/tcg.h
> +++ b/tcg/tcg.h
> @@ -727,7 +727,7 @@ struct TCGContext {
>   
>       uint16_t gen_insn_end_off[TCG_MAX_INSNS];
>       target_ulong gen_insn_data[TCG_MAX_INSNS][TARGET_INSN_START_WORDS];
> -};
> +} QEMU_ALIGNED(64);

Let's drop the alignment and structure re-arrangement for now and focus on the 
task of goto_ptr.


r~