[Nouveau] [Bug 15751] New: nouveau very slow with screen size > 2048

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=15751

           Summary: nouveau very slow with screen size > 2048
           Product: xorg
           Version: git
          Platform: x86 (IA32)
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Driver/nouveau
        AssignedTo: nouveau at lists.freedesktop.org
        ReportedBy: sturnber at gmail.com
         QAContact: xorg-team at lists.x.org


I have two monitors side-by-side using the nouveau driver.  This setup
previously worked fine with the nvidia driver.  In xorg.conf if I set "Virtual
2560 1024" in the Screen section the performance is horrible.  If I set the
width to anything greater than 2048 I have the same problem.  I can set the
screen size to 2048x2048 and awkwardly have the monitors on top of each other
and performance is fine.  It is unclear to me why 2048x2048 would have better
performance than 2560x1024 or even 2304x864.