From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:34099)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1ZPSoB-0000e6-3s
	for qemu-devel@nongnu.org; Wed, 12 Aug 2015 05:58:55 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1ZPSo6-0005wp-2I
	for qemu-devel@nongnu.org; Wed, 12 Aug 2015 05:58:54 -0400
Received: from mail-wi0-x236.google.com ([2a00:1450:400c:c05::236]:32998)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1ZPSo5-0005wO-RV
	for qemu-devel@nongnu.org; Wed, 12 Aug 2015 05:58:50 -0400
Received: by wijp15 with SMTP id p15so210576404wij.0
	for <qemu-devel@nongnu.org>; Wed, 12 Aug 2015 02:58:49 -0700 (PDT)
Sender: Paolo Bonzini <paolo.bonzini@gmail.com>
References: <1439220437-23957-1-git-send-email-fred.konrad@greensocs.com>
	<1439220437-23957-10-git-send-email-fred.konrad@greensocs.com>
	<55C8CE36.1070208@redhat.com> <8737zph9dy.fsf@linaro.org>
	<55CA6A6E.9030205@greensocs.com>
From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <55CB18D5.2020709@redhat.com>
Date: Wed, 12 Aug 2015 11:58:45 +0200
MIME-Version: 1.0
In-Reply-To: <55CA6A6E.9030205@greensocs.com>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [RFC PATCH V7 09/19] Drop global lock during TCG
	code execution
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Frederic Konrad <fred.konrad@greensocs.com>, =?UTF-8?Q?Alex_Benn=c3=a9e?= <alex.bennee@linaro.org>
Cc: mttcg@greensocs.com, a.rigo@virtualopensystems.com, mark.burton@greensocs.com, guillaume.delbergue@greensocs.com, qemu-devel@nongnu.org



On 11/08/2015 23:34, Frederic Konrad wrote:
>>>
>> Also if qemu_cond_broadcast(&qemu_io_proceeded_cond) is being dropped
>> there is no point keeping the guff around in qemu_tcg_wait_io_event.
>>
> Yes good point.
> 
> BTW this leads to high consumption of host CPU eg: 100% per VCPU thread as
> the VCPUs thread are no longer waiting for qemu_io_proceeded_cond.

If the guest CPU is busy waiting, that's expected.  But if the guest CPU
is halted, it should not have 100% host CPU consumption.

Paolo