[Intel-gfx] Reasons for no ring-buffer on 2.6.27?

[Clemens Eisserer]

Hi,

I've played a bit with latest intel/xserver git and noticed very poor
performance on Fedora-10-beta.
When I execute exactly the same x/driver binaries on a self-compiled
2.6.20.1 on Fedora8 performance was as expected (well, actually a bit
worse than I hoped for ;) )

What I noticed was that according to sysprof a lot of time was spent
inside flush-functions like intel-batch-flush (called by
i830exaDoneSolid ~70% and i830sync ~25%), and that some driver
initialization messages differ in Xorg.log.
Any idea why a ring-buffer is initialized and used with 2.6.20.1 and
it works so well for my testcase, but not with 2.6.27?

Should I post the testcase?

Thank you in advance, Clemens

With 2.6.27 I get:
(II) [drm] DRM interface version 1.3
(II) [drm] DRM open master succeeded.
(II) intel(0): [drm] Using the DRM lock SAREA also for drawables.
(II) intel(0): [drm] framebuffer mapped by ddx driver
(II) intel(0): [drm] added 1 reserved context for kernel
(II) intel(0): X context handle = 0x1
(II) intel(0): [drm] installed DRM signal handler
(**) intel(0): Framebuffer compression enabled
(**) intel(0): Tiling enabled
(==) intel(0): VideoRam: 262144 KB
(II) intel(0): Attempting memory allocation with tiled buffers.
(II) intel(0): Tiled allocation successful.
(II) intel(0): [drm] Registers = 0x2ffb0000
(II) intel(0): [drm] Initialized kernel agp heap manager, 33554432
(II) intel(0): [dri] visual configs initialized
(II) intel(0): Page Flipping disabled
(II) intel(0): vgaHWGetIOBase: hwp->IOBase is 0x03d0, hwp->PIOOffset is 0x0000
(II) EXA(0): Offscreen pixmap area of 31457280 bytes


But with 2.6.20.1 I get also notifications about a ring-buffer:
(II) [drm] DRM interface version 1.3
(II) [drm] DRM open master succeeded.
(II) intel(0): [drm] Using the DRM lock SAREA also for drawables.
(II) intel(0): [drm] framebuffer mapped by ddx driver
(II) intel(0): [drm] added 1 reserved context for kernel
(II) intel(0): X context handle = 0x1
(II) intel(0): [drm] installed DRM signal handler
(**) intel(0): Framebuffer compression enabled
(**) intel(0): Tiling enabled
(==) intel(0): VideoRam: 262144 KB
(II) intel(0): Attempting memory allocation with tiled buffers.
(II) intel(0): Tiled allocation successful.
(II) intel(0): [drm] Registers = 0xffd80000
(II) intel(0): [drm] ring buffer = 0xe0000000
(II) intel(0): [drm] mapped front buffer at 0xe1000000, handle = 0xe1000000
(II) intel(0): [drm] mapped back buffer at 0xe4000000, handle = 0xe4000000
(II) intel(0): [drm] mapped depth buffer at 0xe5000000, handle = 0xe5000000
(II) intel(0): [drm] mapped classic textures at 0xe6000000, handle = 0xe6000000
(II) intel(0): [drm] Initialized kernel agp heap manager, 33554432
(II) intel(0): [dri] visual configs initialized
(II) intel(0): Page Flipping disabled
(II) intel(0): vgaHWGetIOBase: hwp->IOBase is 0x03d0, hwp->PIOOffset is 0x0000
(II) EXA(0): Offscreen pixmap area of 31457280 bytes