From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50421) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eMKGv-0005Em-I3 for qemu-devel@nongnu.org; Tue, 05 Dec 2017 15:56:58 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eMKGr-0001nY-LP for qemu-devel@nongnu.org; Tue, 05 Dec 2017 15:56:57 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:41336 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eMKGr-0001nM-FP for qemu-devel@nongnu.org; Tue, 05 Dec 2017 15:56:53 -0500 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vB5KumPl056964 for ; Tue, 5 Dec 2017 15:56:51 -0500 Received: from e32.co.us.ibm.com (e32.co.us.ibm.com [32.97.110.150]) by mx0b-001b2d01.pphosted.com with ESMTP id 2ep2j1h18r-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 05 Dec 2017 15:56:51 -0500 Received: from localhost by e32.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 5 Dec 2017 13:56:50 -0700 References: <1510696349-5151-1-git-send-email-stefanb@linux.vnet.ibm.com> <1510696349-5151-2-git-send-email-stefanb@linux.vnet.ibm.com> <1510736731.4383.4.camel@intel.com> From: Stefan Berger Date: Tue, 5 Dec 2017 15:56:46 -0500 MIME-Version: 1.0 In-Reply-To: <1510736731.4383.4.camel@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Message-Id: <24cf3bb4-546d-0566-cffa-1b863d387db3@linux.vnet.ibm.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v3 for-2.11 1/3] tpm_emulator: Add a caching layer for the TPM Established flag List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Valluri, Amarnath" , "marcandre.lureau@gmail.com" Cc: "qemu-devel@nongnu.org" On 11/15/2017 04:05 AM, Valluri, Amarnath wrote: > On Wed, 2017-11-15 at 04:47 +0100, Marc-Andr=C3=A9 Lureau wrote: >> Hi >> >> On Wed, Nov 15, 2017 at 2:16 AM, Stefan Berger >> wrote: >>> On 11/14/2017 06:40 PM, Marc-Andr=C3=A9 Lureau wrote: >>>> >>>> Hi >>>> >>>> On Tue, Nov 14, 2017 at 10:52 PM, Stefan Berger >>>> wrote: >>>>> >>>>> Add a caching layer for the TPM established flag so that we >>>>> don't >>>>> need to go to the emulator every time the flag is read by >>>>> accessing >>>>> the REG_ACCESS register. >>>> What's the impact? Isn't this just a "small" optimization? Iotw, >>>> why >>>> is this for-2.11? >>> The TIS has a register that contains this flag and that's being >>> polled quite >>> frequently. So it generates a lot of traffic to the emulator. This >>> caching >>> layer gets rid of most of the traffic. >> I didn't notice any problem when doing my tests, I guess Amarnath >> niether. perhaps it's best to delay for after 2.11. > Yes, I could see there is little frequent(21 calls to backend) to get > establish flag, and this patch will help to avoid them. But i still > agree with Marc and tag this as "small" optimization. Can you review it so we have it ready for 2.12? Thanks, Stefan > > - Amarnath