From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51953) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bHq5q-0007pX-6w for qemu-devel@nongnu.org; Tue, 28 Jun 2016 06:18:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bHq5l-0003xl-Fk for qemu-devel@nongnu.org; Tue, 28 Jun 2016 06:18:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53549) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bHq5l-0003xg-9p for qemu-devel@nongnu.org; Tue, 28 Jun 2016 06:18:05 -0400 Date: Tue, 28 Jun 2016 11:17:59 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20160628101759.GF2243@work-vm> References: <1467104499-27517-1-git-send-email-pl@kamp.de> <1467104499-27517-8-git-send-email-pl@kamp.de> <20160628092918.GD2243@work-vm> <577245B7.3090502@kamp.de> <20160628101058.GG13019@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160628101058.GG13019@redhat.com> Subject: Re: [Qemu-devel] [PATCH 07/15] qapi: use mmap for QmpInputVisitor List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: Peter Lieven , kwolf@redhat.com, peter.maydell@linaro.org, mst@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com, kraxel@redhat.com, pbonzini@redhat.com * Daniel P. Berrange (berrange@redhat.com) wrote: > On Tue, Jun 28, 2016 at 11:39:03AM +0200, Peter Lieven wrote: > > Am 28.06.2016 um 11:29 schrieb Dr. David Alan Gilbert: > > > * Peter Lieven (pl@kamp.de) wrote: > > > > this struct is approx 75kB > > > I wonder why it's so large. > > > > > > The stack size in QmpInputVisitor; it's got a 1024 element stack > > > (QIV_STACK_SIZE) and I bet we never use anywhere near that. > > > > > > But even then that's 1024 * a 3 pointer stack object, 24 bytes - > > > I don't see where the rest of that 75kB comes from. > > > > Sorry, I had a wrong size in mind. Its 24736 bytes. But thats > > still larger than expecetd, right? > > > > > I'm a little wary about turning all these malloc's into mmap's > > > because we do seem to use things like input visitors for small > > > things; don't the cost of doing the mmap's add up in time > > > instead of space? > > > > Sure, we should discuss this. The series should act as a base for > > discussion. > > > > None of the things I changed into mmap are continously called > > during VM runtime. So it most likely only happens at setup of the > > vServer. > > QmpInputVisitor is used to parse all QMP monitor commands, so will > be used continuously throughout life of QEMU, often very frequently. > eg When migration is running many monitor commands per second are > expected Does the same input visitor get reused by each command? Dave > > Regards, > Daniel > -- > |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| > |: http://libvirt.org -o- http://virt-manager.org :| > |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| > |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK