On 6/17/05, Adam Jackson <[EMAIL PROTECTED]> wrote: > On Thursday 16 June 2005 22:11, Jon Smirl wrote: > > On 6/16/05, Adam Jackson <[EMAIL PROTECTED]> wrote: > > > I would strongly suggest that we use usermode helpers as much as possible > > > even on linux, since we have the code already written in X and it'll > > > increase the similarity with other platforms. Write it once. Other > > > platforms without an fbdev layer will run the server as root and just > > > fork the modesetter. > > > > > > This would be nice to do even for the classic server if possible. > > > > User mode helpers have their own set of problems. It is really hard to > > build them so that the system doesn't deadlock in low memory > > situations. The OOM process killer can also kill them if it gets > > desperate for memory. Trying to run them can trigger swap storms, etc. > > Several groups are building systems like that on Linux right now - > > FUSE, iSCSI, others. Their success is varied and no one has had > > complete success. > > May I suggest that if you don't have enough memory to change video mode, then > you don't have enough memory anyway. And by induction, if the process to > change modes consumes enough memory to trigger the OOM killer, then you are > memory-starved to begin with.
We just have to think about stuff like this. What if the mode change is needed to display the console messages that we are out of memory, the OOM killer has started, etc. Just because you are out of memory I don't think you want to lose control of the console. The in-kernel version stays working in this case. Other problem areas: The initial mode set to get a working console during the boot process. When things like kdbg are running and user space is frozen Priority inversions, need console to kill the offending app Last year I was strongly in favor of user space mode setting, and if I recall right BenH was against it. Now it looks like we swapped positions. I'm not firmly against it, it is just that various people during the last year have shown me where it can get into trouble. -- Jon Smirl [EMAIL PROTECTED] ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_idt77&alloc_id492&op=click -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
