From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v2 28/30] KVM: x86 emulator: restart string instruction without going back to a guest. Date: Mon, 15 Mar 2010 12:24:43 +0200 Message-ID: <4B9E0AEB.3020602@redhat.com> References: <1268583675-3101-1-git-send-email-gleb@redhat.com> <1268583675-3101-29-git-send-email-gleb@redhat.com> <4B9D1545.2020902@redhat.com> <20100314180625.GB5406@redhat.com> <4B9DE55A.5070003@redhat.com> <20100315094447.GG4294@redhat.com> <4B9E0450.4090403@redhat.com> <20100315100756.GH4294@redhat.com> <4B9E08BA.7090303@redhat.com> <20100315101956.GI4294@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: mtosatti@redhat.com, kvm@vger.kernel.org To: Gleb Natapov Return-path: Received: from mx1.redhat.com ([209.132.183.28]:17083 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964838Ab0COKYp (ORCPT ); Mon, 15 Mar 2010 06:24:45 -0400 Received: from int-mx08.intmail.prod.int.phx2.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o2FAOiox031654 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 15 Mar 2010 06:24:44 -0400 Received: from cleopatra.tlv.redhat.com (cleopatra.tlv.redhat.com [10.35.255.11]) by int-mx08.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o2FAOh1E008343 for ; Mon, 15 Mar 2010 06:24:44 -0400 In-Reply-To: <20100315101956.GI4294@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 03/15/2010 12:19 PM, Gleb Natapov wrote: > On Mon, Mar 15, 2010 at 12:15:22PM +0200, Avi Kivity wrote: > >> On 03/15/2010 12:07 PM, Gleb Natapov wrote: >> >>> >>>> Or we can make the buffer larger for everyone (outside this patchset >>>> though). >>>> >>>> >>> I am not sure what do you mean here. INS read ahead and MMIO read cache are >>> different beasts. Former is needed to speed-up string pio reads, later >>> (not yet implemented) is needed to reread previous MMIO read results in >>> case instruction emulation is restarted due to need to exit to userspace. >>> MMIO read cache need to be invalidated on each iteration of string >>> instruction. >>> >> Instructions with multiple reads or writes need an mmio read/write >> buffer that can be replayed on re-execution. >> >> buffer != cache! A cache can be dropped (perhaps after flushing it >> to a backing store), but a buffer in general cannot. >> >> > That is just naming. Call it "buffer" if you want. > > I still don't understand what do you mean by "Or we can make the buffer > larger for everyone". Who is this "everyone"? Different instruction need > different kind of buffers. > Many instructions can issue multiple reads, ins is just one of them. A generic mmio buffer can be used by everyone. -- error compiling committee.c: too many arguments to function