Re: [patch] Real-Time Preemption, -RT-2.6.12-rc1-V0.7.41-07

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wed, 2005-03-23 at 08:16 +0100, Ingo Molnar wrote:
> * Ingo Molnar <[email protected]> wrote:
> 
> > That callback will be queued on CPU#2 - while the task still keeps
> > current->rcu_data of CPU#1. It also means that CPU#2's read counter
> > did _not_ get increased - and a too short grace period may occur.
> > 
> > it seems to me that that only safe method is to pick an 'RCU CPU' when
> > first entering the read section, and then sticking to it, no matter
> > where the task gets migrated to. Or to 'migrate' the +1 read count
> > from one CPU to the other, within the scheduler.
> 
> i think the 'migrate read-count' method is not adequate either, because
> all callbacks queued within an RCU read section must be called after the
> lock has been dropped - while with the migration method CPU#1 would be
> free to process callbacks queued in the RCU read section still active on
> CPU#2.
> 
how about keeping the rcu callback list in process context and only
splice it to a global (per cpu) list on rcu_read_unlock?

Kind regrads,

Peter Zijlstra

-- 
Peter Zijlstra <[email protected]>

-
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/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux