Dave Airlie skrev: > On Tue, Jun 23, 2009 at 9:35 PM, Peter Zijlstra<pet...@infradead.org> wrote: > >> On Mon, 2009-06-22 at 19:26 +0200, Jerome Glisse wrote: >> >>> We don't need to allocated contiguous pages in cs codepath >>> so use vmalloc instead. >>> >> Best would be to not require >PAGE_SIZE allocations at all of course. >> > > It gets messy when you have copy from user and spinlocks, it would be nice > to just parse the userspace PAGE_SIZE at a time, but it would mean dropping > a lock we probably need to hold. > > >> But barring that, it would be great to have something like: >> >> ptr = kmalloc(size, GFP_KERNEL | __GFP_NOWARN); >> if (!ptr) >> ptr = vmalloc(size); >> > > we have a drm_calloc_large workaround already for the Intel driver which also > need this. > One problem with multiple vmallocs per command submission is performance. Judging from previous work, drivers that are doing this tend to get very cpu-hungry. Since Radeon is only allowing a single process into the command submission path at once, what about pre-allocating a single larger vmalloced buffer at first command submission and take care to flush user-space before the submitted command stream gets too big.
>> Also, how long do these allocations live? vmalloc space can be quite >> limited (i386) and it can fragment too. >> > > Only an ioctl lifetime so they aren't that bad. We however do have some vmaps > that might be quite large, mainly the fbcon framebuffer (up to 8MB in > some cases) > That one would be ioremapped, not vmapped right? Not that it matters because it's using vmalloc space anyway, but it wouldn't be worse than a traditionally ioremapped framebuffer. Thomas > Dave. > > ------------------------------------------------------------------------------ > Are you an open source citizen? Join us for the Open Source Bridge conference! > Portland, OR, June 17-19. Two days of sessions, one day of unconference: $250. > Need another reason to go? 24-hour hacker lounge. Register today! > http://ad.doubleclick.net/clk;215844324;13503038;v?http://opensourcebridge.org > -- > _______________________________________________ > Dri-devel mailing list > Dri-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/dri-devel > ------------------------------------------------------------------------------ Are you an open source citizen? Join us for the Open Source Bridge conference! Portland, OR, June 17-19. Two days of sessions, one day of unconference: $250. Need another reason to go? 24-hour hacker lounge. Register today! http://ad.doubleclick.net/clk;215844324;13503038;v?http://opensourcebridge.org -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
