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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] [4600] variable dynamic translation buffer size
Date: Wed, 28 May 2008 13:55:52 +0100
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To: qemu-devel@nongnu.org

On Wednesday 28 May 2008, Fabrice Bellard wrote:
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0code_gen_buffer =3D mmap(NULL, code_gen_buff=
er_size,
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 PROT_WRITE | PROT_READ | PROT_EXEC,
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 flags, -1, 0);

I'd expect this to cause a significant performance regression on hosts that=
=20
have limited branch range (i.e. everything except x86). The mmap region is=
=20
almost never close to the application text segment, so all helper calls hav=
e=20
to be indirect.

Paul