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Re: [Qemu-devel] [PATCH 01/17] tcg: extend max tcg opcodes on 32bit
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH 01/17] tcg: extend max tcg opcodes on 32bit |
Date: |
Mon, 18 Apr 2011 20:42:29 +0200 |
User-agent: |
Mutt/1.5.20 (2009-06-14) |
On Fri, Apr 15, 2011 at 05:32:42PM +0200, Alexander Graf wrote:
> When running on a 32 bit host, we tend to use more TCG ops than on
> a 64 bit host. Reflect that in the reserved opcode amount constant.
>
> Signed-off-by: Alexander Graf <address@hidden>
> ---
> exec-all.h | 4 ++++
> 1 files changed, 4 insertions(+), 0 deletions(-)
I really like this solution as it is actually better than incrementing
this value for both 32- and 64-bit hosts. That said, I think it should
only be done for 64-bit guests on 32-bit hosts. 32-bit guests on 32-bit
hosts should not use more ops than 32-bit guests on 64-bit hosts.
I think we should do the same for TCG_MAX_OP_SIZE, as it tends the be
the same issue, ie emulating 64-bit load/store on a 32-bit hosts use a
lot of host instructions. That said in that case we should probably
rollback to the previous value on 64-bit hosts. You can do it in the
next version of the patch, but it's nothing mandatory for s390x.
> diff --git a/exec-all.h b/exec-all.h
> index 496c001..d23a36d 100644
> --- a/exec-all.h
> +++ b/exec-all.h
> @@ -43,7 +43,11 @@ typedef ram_addr_t tb_page_addr_t;
> typedef struct TranslationBlock TranslationBlock;
>
> /* XXX: make safe guess about sizes */
> +#if HOST_LONG_BITS == 32
> +#define MAX_OP_PER_INSTR 128
> +#else
> #define MAX_OP_PER_INSTR 96
> +#endif
>
> #if HOST_LONG_BITS == 32
> #define MAX_OPC_PARAM_PER_ARG 2
> --
> 1.6.0.2
>
>
>
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
- Re: [Qemu-devel] [PATCH 09/17] s390x: virtio machine storage keys, (continued)
- [Qemu-devel] [PATCH 03/17] linux-user: define a couple of syscalls for non-uid16 targets, Alexander Graf, 2011/04/15
- [Qemu-devel] [PATCH 05/17] kvm: add kvm stub for arch specific stuff, Alexander Graf, 2011/04/15
- [Qemu-devel] [PATCH 08/17] s390x: Dispatch interrupts to KVM or the real CPU, Alexander Graf, 2011/04/15
- [Qemu-devel] [PATCH 13/17] s390x: Adjust internal kvm code, Alexander Graf, 2011/04/15
- [Qemu-devel] [PATCH 01/17] tcg: extend max tcg opcodes on 32bit, Alexander Graf, 2011/04/15
- Re: [Qemu-devel] [PATCH 01/17] tcg: extend max tcg opcodes on 32bit,
Aurelien Jarno <=
- [Qemu-devel] [PATCH 06/17] s390x: Prepare cpu.h for emulation, Alexander Graf, 2011/04/15
- [Qemu-devel] [PATCH 07/17] s390x: Enable s390x-softmmu target, Alexander Graf, 2011/04/15
- [Qemu-devel] [PATCH 10/17] s390x: keep hint on virtio managing size, Alexander Graf, 2011/04/15
- [Qemu-devel] [PATCH 02/17] s390x: s390x-linux-user support, Alexander Graf, 2011/04/15