On Tue, Nov 24, 2015 at 07:06:21PM +0100, Daniel Vetter wrote: > Just setting obj->dirty only works if you also have the pages. Exactly. The CPU access has historically always been page-by-page. The style here more or less to emulate the CPU mmap. > But it's also not awesome that set_to_gtt_domain does this for callers. Hmm, do you have an example where we want set-to-gtt(write), but not actually write through the backing storage? Internal use of set-to-gtt has never been ideal (e.g. context) but we haven't yet come up with a better semantic. > For lack of clear solutions I'd go with sprinkling obj->dirty or > page_set_dirty over callers. Aside: relocate_entry_cpu probably gets away > because of the unconditional obj->dirty we do later on, and that we redo > all relocs if a fault happens. Still would be good to fix it, just for > safety. [copy_batch() isn't a bug as the contents are invalidated after use anyway] relocate_entry_cpu() is a bug we never caught. Indeed we've papered over it to mask some over userspace issues, but just adding the set_page_dirty() as required isn't going to be a big hardship. We have tons of swapthrash tests to check persistency of GPU buffers, but we never tried to thrash the batches themselves out to swap and then reuse them. I guess that it is because userspace doesn't reuse batches that we never had report of the issue. Hibernating would be a good exercise of such. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
