From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59069) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X79Us-0006lS-J5 for qemu-devel@nongnu.org; Tue, 15 Jul 2014 16:38:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1X79Um-0004nx-EK for qemu-devel@nongnu.org; Tue, 15 Jul 2014 16:38:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:27775) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X79Um-0004nt-5t for qemu-devel@nongnu.org; Tue, 15 Jul 2014 16:38:40 -0400 Message-ID: <53C59148.3020501@redhat.com> Date: Tue, 15 Jul 2014 22:38:32 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1405424541-21803-1-git-send-email-alex.bennee@linaro.org> <1405424541-21803-4-git-send-email-alex.bennee@linaro.org> <53C52A66.5000906@redhat.com> <871ttmyabr.fsf@linaro.org> <53C58AF6.40206@redhat.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 3/3] trace: instrument and trace tcg tb flush activity List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= , =?UTF-8?B?QWxleCBCZW5uw6ll?= , QEMU Developers , Stefan Hajnoczi , mohamad.gebai@gmail.com Il 15/07/2014 22:29, Peter Maydell ha scritto: >> > >> > I think it's not a big deal if you always enable the counting, and perhaps >> > show them in "info jit". > We don't enable any other tracepoints by default; why would > we want to enable just this one which is in a hot codepath?? I'm not referring to the tracepoint, only to trace_inc_counter instead of just "x++". The overhead is probably not measurable. There are a few low-hanging fruit optimizations in cpu-exec.c that probably would give more measurable benefit, for example trying to replace cpu_loop_exit with a goto whenever possible. Paolo