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

Re: [Xen-devel] [v3,11/41] mips: reuse asm-generic/barrier.h

On 01/14/2016 08:16 AM, Paul E. McKenney wrote:
On Thu, Jan 14, 2016 at 12:04:45PM +0000, Will Deacon wrote:
On Wed, Jan 13, 2016 at 12:58:22PM -0800, Leonid Yegoshin wrote:
On 01/13/2016 12:48 PM, Peter Zijlstra wrote:
On Wed, Jan 13, 2016 at 11:02:35AM -0800, Leonid Yegoshin wrote:

I ask HW team about it but I have a question - has it any relationship with
replacing MIPS SYNC with lightweight SYNCs (SYNC_WMB etc)?
Of course. If you cannot explain the semantics of the primitives you
introduce, how can we judge the patch.

You missed a point - it is a question about replacement of SYNC with
lightweight primitives. It is NOT a question about multithread system
behavior without any SYNC. The answer on a latest Will's question lies in
different area.
What Will said!

Yes, you can cut corners within MIPS architecture-specific code,
but primitives that are used in the core kernel really do need to
work as expected.

                                                        Thanx, Paul

Absolutelly! Please use SYNC - right now it is not.

An the only point - please use an appropriate SYNC_* barriers instead of heavy bold hammer. That stuff was design explicitly to support the requirements of Documentation/memory-barriers.txt

It is easy - just use smp_acquire instead of plain smp_mb insmp_load_acquire, at least for MIPS.

- Leonid.
- Leonid.

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.