Bug 15751

Summary:	nouveau very slow with screen size > 2048
Product:	xorg	Reporter:	Scott Turnberg <sturnber>
Component:	Driver/nouveau	Assignee:	Nouveau Project <nouveau>
Status:	RESOLVED INVALID	QA Contact:	Xorg Project Team <xorg-team>
Severity:	normal
Priority:	medium	CC:	saulius2
Version:	git
Hardware:	x86 (IA32)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:
Bug Depends on:
Bug Blocks:	21186

Description Scott Turnberg 2008-04-28 20:24:15 UTC

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.  

From lspci:
VGA compatible controller: nVidia Corporation NV18 [GeForce4 MX 4000] (rev c1)

Comment 1 Maarten Maathuis 2008-04-29 00:41:05 UTC

The reason is quite simple, above 2048x2048 2d acceleration is completely turned off. I don't know if this limit is the right one for NV17/NV18, being a mixed gf2/gf4 design.

Comment 2 Maarten Maathuis 2008-04-29 00:50:50 UTC

Some more googling reveals it might be the correct limit. Even with this limitation it's theoretically possible to use the monitors the way you want (giving each crtc their own texture, which would work). There is a prototype called shatter (which ofcource requires driver modifications), so there is hope for the future.

Comment 3 Scott Turnberg 2008-04-29 07:57:39 UTC

Thanks for the quick reply.  I'll keep an eye out for the develpment of shatter.

Comment 4 Ilia Mirkin 2013-08-18 18:09:27 UTC

It appears that this bug report has laid dormant for quite a while. Sorry we haven't gotten to it. Since we fix bugs all the time, chances are pretty good that your issue has been fixed with the latest software. Please give it a shot. (Linux kernel 3.10.7, xf86-video-nouveau 1.0.9, mesa 9.1.6, or their git versions.) If upgrading to the latest isn't an option for you, your distro's bugzilla is probably the right destination for your bug report.

In an effort to clean up our bug list, we're pre-emptively closing all bugs that haven't seen updates since 2011. If the original issue remains, please make sure to provide fresh info, see http://nouveau.freedesktop.org/wiki/Bugs/ for what we need to see, and re-open this one.

Thanks,

The Nouveau Team

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