From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v2] posix-aio-compat: fix latency issues Date: Sun, 28 Aug 2011 11:09:03 +0300 Message-ID: <4E59F79F.1030504@redhat.com> References: <1313294689-21572-1-git-send-email-avi@redhat.com> <4E5291DF.1070603@siemens.com> <4E539FA9.3010507@codemonkey.ws> <4E53A4E4.1090807@siemens.com> <4E53B2D8.7080608@codemonkey.ws> <4E53B4C9.3070906@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Kevin Wolf , Stefan Hajnoczi , "kvm@vger.kernel.org" , "qemu-devel@nongnu.org" To: Jan Kiszka Return-path: In-Reply-To: <4E53B4C9.3070906@siemens.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org List-Id: kvm.vger.kernel.org On 08/23/2011 05:10 PM, Jan Kiszka wrote: > On 2011-08-23 16:02, Anthony Liguori wrote: > > On 08/23/2011 08:02 AM, Jan Kiszka wrote: > >> On 2011-08-23 14:40, Anthony Liguori wrote: > >>> You should be able to just use an eventfd or pipe. > >>> > >>> Better yet, we should look at using GThreadPool to replace posix-aio-compat. > >> > >> When interacting with the thread pool is part of some time-critical path > >> (easily possible with a real-time Linux guest), general-purpose > >> implementations like what glib offers are typically out of the game. > >> They do not provide sufficient customizability, specifically control > >> over their internal synchronization and allocation policies. That > >> applies to the other rather primitive glib threading and locking > >> services as well. > > > > We can certainly enhance glib. glib is a cross platform library. I > > Do you want to carry forked glib bits in QEMU? We can make real-time depend on a newer glib version. > > > don't see a compelling reason to invent a new cross platform library > > just for QEMU especially if the justification is future features, not > > current features. > > Tweaking affinity of aio threads is already a current requirement. > > And we already have a working threading and locking system. One that is > growing beyond glib's level of support quickly (think of RCU). > glib will have to support RCU as well. But for this topic, I agree with you for now. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.