lkml.org 
[lkml]   [2016]   [Feb]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH tip/core/rcu 02/14] documentation: Fix control dependency and identical stores
On Thu, Feb 25, 2016 at 5:40 AM, Paul E. McKenney
<paulmck@linux.vnet.ibm.com> wrote:
> So ordering between the read from "a" and the write to "b" is still
> preserved. The reason this works is that the smp_mb() does all the
> ordering, so the fact that the control dependency has been eliminated
> is irrelevant.


Thanks, Paul, nice clarification.

I thinks this example qualifies as an good example to demonstrate the subtle
scope of effect of these two level barriers.

A vivid example is always better for understanding instead of learning
"barrier() is compiler-level
barrier, and smp_*mb() is processor-level barrier" by rote ,
especially for the new comers to memory-barriers.txt. ;-)




Thanks,
Jianyu Zhan

\
 
 \ /
  Last update: 2016-02-25 08:21    [W:0.078 / U:0.164 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site