Messages in this thread | | | Date | Fri, 10 Dec 2010 13:51:23 -0600 (CST) | From | Christoph Lameter <> | Subject | Re: [BUG] 2.6.37-rc3 massive interactivity regression on ARM |
| |
On Fri, 10 Dec 2010, Peter Zijlstra wrote:
> > > gcc wont be able to do this yet (%fs/%gs selectors) > > > > The kernel can do that using the __percpu annotation. > > That's not true: > > # define __percpu > > Its a complete NOP.
The annotation serves for sparse checking. .... If you do not care about those checks then you can simply pass a percpu pointer in the same form as a regular pointer.
> > > But we can provide this_cpu_write_seqcount_{begin|end}() > > > > No we cannot do hat. this_cpu ops are for per cpu data and not for locking > > values shared between processors. We have a mechanism for passing per cpu > > pointers with a corresponding annotation. > > -enoparse, its not locking anything, is a per-cpu sequence count.
seqlocks are for synchronization of objects on different processors.
Seems that you do not have that use case in mind. So a seqlock restricted to a single processor? If so then you wont need any of those smp write barriers mentioned earlier. A simple compiler barrier() is sufficient.
| |