Re: X-Server 1.5.0 very sluggish

[Owen Taylor <otaylor@xxxxxxxxxx>]

On Mon, 2008-09-15 at 18:58 +0200, Michel Dänzer wrote:> On Mon, 2008-09-15 at 12:31 -0400, Owen Taylor wrote:> > > > I don't have any immediate ideas, but I wanted to throw in the data> > point that I also seem to see a sudden slowness on r300+EXA moving from> > 1.4.99 snapshot from July 2 (current F9 packages) to 1.5.0. Somewhat> > similar to what you describe, though not nearly as extreme. (Some> > windows take a couple of seconds to repaint, but menus are normal.) > > > > This is leaving the radeon driver, mesa, etc, unchanged, and only> > upgrading the X server.> > > > The slowness seems to be triggered by rendering UI elements in the GTK+> > theme I'm using (Clearlooks, AFAIK) ... so it would be some sort of> > problem with Render acceleration of gradients, masks, or similar. > > > > Looking at sysprof output, most of the time during sluggish redrawing> > is spent migrating pixmaps from video memory into system memory inside a> > Composite operation, so it appears that for some reason, software> > fallbacks are being triggered. The sysprof output, unfortunately doesn't> > have enough detail to be able to tell why that is happening.> > Can one of you guys bisect this regression?
Working on it ... right now it looks like:
 - XShm pixmaps got accidentally reenabled in the course of    Adam's changes - Someone (maybe GTK, having tracked it down yet) is taking advantage     of that by creating a shared pixmap and using it as the source for   a composite operation. - That is not handled well in EXA and triggers migration of the   destination back to system memory. (*)
- Owen
(*) One of the many cases where we'd be better off creating temporariesin video memory to avoid migration.

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