ProcPutImage calls exaDoMoveOutPixmap, 4x slowdown

[Clemens Eisserer]

Hello,

I've a use-case where the client uploads 32x32 A8 images to an
256x256x8 pixmap  which is later used as mask in a composition
operation.
The test-case is able to render with 40fps on xserver-1.3/intel-2.1.1
however with the latest GIT of both I only get ~10-15fps.
Unfourtunatly I've not been able to create a stand-alone testcase
which triggers this problem :-/

Using sysprof I can see a lot of time is spent moving data arround,
very strange is that PutImage seems to cause a readback:
ProcPutImage->ExaCheckPutImage->exaPrepareAccessReg->exaDoMigration->exaDoMoveOutPixmap->exaCopyDirty->exaWaitSync->I830EXASync
In Composite I see the re-uploading again.

Any idea why ProcPutImage could to fallback (there's plenty of free vram)?
Are there tools / settings which could help me to identify the problem?

Thank you in advance, Clemens