Messages in this thread | | | Date | Tue, 25 Jun 2013 23:49:47 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH RFC nohz_full 0/8] Provide infrastructure for full-system idle |
| |
On Tue, 25 Jun 2013, Paul E. McKenney wrote: > Note that this version pays attention to CPUs that have taken an NMI > from idle. It is not clear to me that NMI handlers can safely access > the time on a system that is long-term idle. Unless someone tells me > that it is somehow safe to access time from an NMI from idle, I will > remove NMI support in the next version.
NMI cannot access any time related functions independent of NOHZ, long term idle or whatever you come up with:
write_seqcount_begin(&timekeeper_seq);
---> NMI ... do { seq = read_seqcount_begin(&timekeeper_seq); } while (read_seqcount_retry(&timekeeper_seq, seq));
Guess how well that works ....
Thanks,
tglx
| |