From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Petazzoni Date: Thu, 4 Aug 2016 18:28:25 +0200 Subject: [Buildroot] Raspberry Pi OpenGL/Qt5 10x slower than Raspbian In-Reply-To: References: <20160804091707.6755bb66@free-electrons.com> Message-ID: <20160804182825.4c9ff4ff@free-electrons.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Hello, On Thu, 4 Aug 2016 08:35:24 -0400, Frank Hunleth wrote: > > Change -Os by -O2 in the Buildroot configuration, by using > > BR2_OPTIMIZE_2. I even believe we should stop using BR2_OPTIMIZE_S by > > default, and switch to BR2_OPTIMIZE_2 instead. > > Done, but no luck for this particular issue. I have another piece of > code that differs in performance from Debian by 5% and is more CPU > bound. I'll try it on that too. Gaah. > > Also, are you sure it's really using OpenGL with the Buildroot build? > > On the Buildroot build, I've tried running the Qt application with > "-platform eglfs", but that seemed to be the default already. I'm not > sure how to check deeper than that. I guess if eglfs support has been built and you're able to use, it means that it's using the GPU. > > Under Raspbian, are you also running the eglfs build of Qt, or is it > > with X.org? I'm not sure Debian has an eglfs capable build of Qt5. > > You're right. On Raspbian, I'm running with X.org. I am naively > assuming that Qt5 w/ eglfs isn't 10x slower than Qt5 w/ X.org. I > really hope that's not the case. I also hope, but using X.org on one side and doing eglfs on the other side is really a very different configuration. I would also assume that there should not be a 10x difference between Qt5/X.org vs Qt5/eglfs, but I have never tested, so I don't know. Which toolchain are you using ? Are you building everything optimized for ARMv6 (assuming you're using Rpi1) ? But a 10x difference really feels like acceleration is not used at all. You can also check the CPU consumption while running your Qt app to see what it looks like. Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com