On Sat, Jul 12, 2014 at 12:46:43PM -0700, Chris Cappuccio wrote: > Kevin Chadwick [ma1l1i...@yahoo.co.uk] wrote: > > > > I'm guessing this is due to the new KMS 3d support not being as fast > > right now but much better than you had before. > > > > It also affects Thunderbird. Here's my synopsis of Mark Kettenis's > analysis: > > Firefox uses an old version of cairo. This cairo library uses XGetImage > to get the image copied back to a ZPixmap in user space. It copies with > a 4k buffer size (the default). So your extremely large, uncompressed image > gets copied in 4k chunks with constant context switches. > > Not only do the subsystems thrash themselves, but the server sends the > image in non-blocking mode, and the socket buffer is full, it fails with > EAGAIN and discards the data already sent by copying the remaining data to > the start of the buffer, waits for the socket to drain and tries again when > the socket is ready. > > You can find Mark's buffer size improvement here: > http://comments.gmane.org/gmane.os.openbsd.cvs/128950 > http://lists.x.org/archives/xorg-devel/2014-March/041543.html > > This makes the problem less apparent. > > Some in the ports tree tried using a newer cairo and found a whole new > set of problems (apparently firefox depends on old cairo and/or local > modifications to it) > > Why Firefox needs a ZPixmap of the image displayed, that is, the entire > fully uncompressed image copied back to userland in 4k (or 64k) chunks, > that's totally beyond me, by itself. Why the X server does it in such > a poor way, beyond me. It's crazyland!!!
The new gtk3 flavor doesn't use the internal version of cairo. > > > Playing video in browsers and even displaying pictures is a > > surprisingly resource hungry task with umpteen potential rules working > > out what shape and where everything should be and unfortunately more > > effort has been spent on javascript performance than rendering. > > These issues are not directly related (and largely solved when the X > clients use the right techniques, which sometimes vary between platforms > and display drivers) > > Chris > -- Juan Francisco Cantero Hurtado http://juanfra.info
