On Jun 12, 2015 1:43 AM, "Borislav Petkov" <b...@suse.de> wrote: > > On Tue, Jun 09, 2015 at 09:46:52AM -0700, Andy Lutomirski wrote: > > I don't like this hack. The compiler is entirely within is rights to > > poke addr's cacheline (i.e. the stack) between the two instructions. > > I'd suggest either making the thing a full cacheline long or using a > > single asm statement. > > How about this: > > /* > * This should be a memory location in a cache line which is > * unlikely to be touched by other processors. The actual > * content is immaterial as it is not actually modified in any way. > */ > mwait_ptr = ¤t_thread_info()->flags; > > and then > > __monitor(mwait_ptr, 0, 0); > > We already do this in mwait_play_dead(). > > However, am I even correct in assuming that ->flags won't really be > touched as we're doing delay() and nothing pokes into current anyway?
We poke flags remotely, but not frequently enough for this to be a problem. However, I don't know that touching current in udelay is okay. How about some read-mostly percpu variable, such as cpu_tss? --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
