Jerome Glisse wrote: > On Tue, Feb 23, 2010 at 02:05:50PM +0100, Thomas Hellstrom wrote: > >> Jerome Glisse wrote: >> >>> On Mon, Feb 22, 2010 at 08:58:28PM +0100, Thomas Hellstrom wrote: >>> >>>> Jerome Glisse wrote: >>>> >>>>> On Mon, Feb 22, 2010 at 06:30:24PM +0100, Thomas Hellstrom wrote: >>>>> >>>>>> Jerome Glisse wrote: >>>>>> >>>>>>> Thomas i think i addressed your concern here, the ttm_bo_validate >>>>>>> didn't needed a new argument or i did not understand what was >>>>>>> necessary beside no_wait. In this patchset we check the value >>>>>>> of callback in case of EBUSY (call set_need_resched) or ERESTARTSYS >>>>>>> we return VM_FAULT_NOPAGE. >>>>>>> >>>>>> Well, if we from the fault callback call any function that might >>>>>> call ttm_bo_reserve or ttm_bo_reserve_locked, we must make sure >>>>>> that we never wait, but return -EBUSY all the way back to the >>>>>> fault function. Such a case may be ttm_bo_validate that calls >>>>>> ttm_bo_evict_first, or something causing a swapout... >>>>>> ttm_bo_validate currently doesn't have that functionality, >>>>>> because @no_wait just means don't wait for GPU. >>>>>> >>>>> What do you mean by never wait ? Is this GPU wait ? or CPU wait ie don't >>>>> use mutex or kernel code path that might sleep ? >>>>> >>>> I mean waiting while reserving a bo. (If another thread has the bo >>>> reserved). >>>> >>>> >>>>> After a new review i don't think we ever wait for the GPU with the current >>>>> patch and as far as i can tell we will return EBUSY or ERESTART all the >>>>> way up. >>>>> >>>>> Cheers, >>>>> Jerome >>>>> >>>> If there is *no* code path trying to reserve a bo or create a >>>> user-space visible object from within the fault handler, it should >>>> be ok. >>>> >>>> /Thomas >>>> >>>> >>>> >>> Did a new review again here is the call chain : >>> ttm_bo_move_buffer >>> ttm_bo_mem_space >>> ttm_bo_mem_force_space >>> ttm_mem_evict_first >>> ttm_bo_reserve_locked (no_wait = true) >>> >> Here ttm_mem_evict_fist may wait for unreserve IIRC (the -EBUSY >> return from ttm_bo_reserve_locked) is not propagated back. >> > > The code is not straightforward but if no_wait is true the > -EBUSY of ttm_bo_reserve_locked will be propagated back. >
The point is that we don't want to set no_wait to true, because it's OK to wait for GPU. We want to add an extra argument no_wait_reserve. /Thomas ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
