From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:36533) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QBtP7-0000Bf-M5 for qemu-devel@nongnu.org; Mon, 18 Apr 2011 14:42:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QBtP6-0007tL-Eb for qemu-devel@nongnu.org; Mon, 18 Apr 2011 14:42:33 -0400 Received: from hall.aurel32.net ([88.191.126.93]:42045) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QBtP6-0007t6-7E for qemu-devel@nongnu.org; Mon, 18 Apr 2011 14:42:32 -0400 Date: Mon, 18 Apr 2011 20:42:29 +0200 From: Aurelien Jarno Message-ID: <20110418184229.GF16178@volta.aurel32.net> References: <1302881578-5357-1-git-send-email-agraf@suse.de> <1302881578-5357-2-git-send-email-agraf@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1302881578-5357-2-git-send-email-agraf@suse.de> Subject: Re: [Qemu-devel] [PATCH 01/17] tcg: extend max tcg opcodes on 32bit List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf Cc: peter.maydell@linaro.org, QEMU-devel Developers , Richard Henderson 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 > --- > 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 aurelien@aurel32.net http://www.aurel32.net