On Tue, May 06, 2014 at 04:40:58PM +0530, sourab.gupta@xxxxxxxxx wrote: > From: Sourab Gupta <sourab.gupta@xxxxxxxxx> > > This patch is in continuation of and is dependent on earlier patch > series to 'reduce the time for which device mutex is kept locked'. > (http://lists.freedesktop.org/archives/intel-gfx/2014-May/044596.html) > > This patch aims to reduce the allocation time of pages from shmem > by using blitter engines for clearing the pages freshly alloced. > This is utilized in case of fresh pages allocated in shmem_preallocate > routines in execbuffer path and page_fault path only. > > Even though the CPU memset routine is optimized, but still sometimes > the time consumed in clearing the pages of a large buffer comes in > the order of milliseconds. > We intend to make this operation asynchronous by using blitter engine, > so irrespective of the size of buffer to be cleared, the execbuffer > ioctl processing time will not be affected. Use of blitter engine will > make the overall execution time of 'execbuffer' ioctl lesser for > large buffers. > > There may be power implications here on using blitter engines, and > we have to evaluate this. As a next step, we can selectively enable > this HW based memset only for large buffers, where the overhead of > adding commands in a blitter ring(which will otherwise be idle), > cross ring synchronization, will be negligible compared to using the > CPU to clear out the buffer. You leave a lot of holes by which you leak the uncleared pages to userspace. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
