On Sat, 2007-07-14 at 21:16 +0400, Oleg Nesterov wrote: > On 07/14, Peter Zijlstra wrote: > > > > From: Mathieu Desnoyers <[EMAIL PROTECTED]> > > > > This patch adds the ability to protect critical sections from migration to > > another CPU without disabling preemption. > > > > This will be useful to minimize the amount of preemption disabling for the > > -rt > > patch. It will help leveraging improvements brought by the local_t types in > > asm/local.h (see Documentation/local_ops.txt). Note that the updates done to > > variables protected by migrate_disable must be either atomic or protected > > from > > concurrent updates done by other threads. > > > > Typical use: > > > > migrate_disable(); > > local_inc(&__get_cpu_var(&my_local_t_var)); > > migrate_enable(); > > > > Which will increment the variable atomically wrt the local CPU. > > I still think this patch is buggy. Perhaps I am wrong. Please look at > > http://marc.info/?l=linux-kernel&m=118417177818825 > > there was no any reply.
Looking at it, I tend to agree that the migration_thread thing is indeed quite broken. Not quite sure on how to solve it nicely though, one would need to stick the migration request structure somewhere in task_struct or thread_info, and not back on the migration_queue. But given that people already complained about the adding ov migration_counter,. I'm not daring to propose such things. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
