On 02/21/2013 05:21 AM, Matthew Helsley wrote: > On Thu, Feb 14, 2013 at 8:18 AM, Pavel Emelyanov <xemul@xxxxxxxxxxxxx> wrote: >> Hi. >> >> I'm working on the checkpoint-restore project (http://criu.org), briefly >> it's aim is to collect information about process' state and saving it so >> that later it is possible to recreate the processes in the very same state >> as they were, using the collected information. >> >> One part of the task's state is the posix timers that this task has created. >> Currently kernel doesn't provide any API for getting information about >> what timers are currently created by process and in which state they are. >> I'd like to extend the posix timers API to provide more information about >> timers. >> >> Another problem with timers is the timer ID. Currently IDs are generated >> from global IDR and this makes it impossible to restore a timer from >> the saved state in general, as the required ID may be already busy at the >> time of restore. >> >> That said, I propose to >> >> 1. Change the way timer IDs are generated. This was done some time ago, so >> I'm just re-sending this patch; > > Seems fine in principle. Aside: I noticed there were some > important-looking patches to the idr usage in timer id allocation > today... Hm, OK, will try to find one. >> 2. Add a system call that will list timer IDs created by the calling process; > > If timers were listed in /proc like fds then you wouldn't need this > syscall. If we keep adding new syscalls like this CRIU will be > needlessly x86-specific when it could have been written more portably. > >> 3. Add a system call that will allow to get the sigevent information about >> particular timer in the sigaction-like manner. > > You mentioned "extending the POSIX timer API". Isn't that something > best left to standards bodies lest your changes conflict with theirs? > Again, if this were a /proc interface you wouldn't have that issue > (you'll have others ;)). > >> >> This is actually an RFC to start discussion about how the described problems >> can be addressed. Thus, if the approach with new system calls is not acceptable, >> I'm OK to implement this in any other form. > > My preference is for "other form" for the reasons above. No problem, proc is OK for me as well. I will look at what can be done here. Thanks for the feedback! > Cheers, > -Matt Helsley > . > -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
