search for: read_point

...00, Michael S. Tsirkin wrote: > READ_ONCE is really all over the place (some code literally replaced all > memory accesses with READ/WRITE ONCE). Yeah, so? Complain to the compiler people for forcing us into that. > Would an API like WRITE_POINTER()/smp_store_pointer make sense, > and READ_POINTER for symmetry? No, the whole point of the exercise was to get away from the fact that dependent loads are special.

...00, Michael S. Tsirkin wrote: > READ_ONCE is really all over the place (some code literally replaced all > memory accesses with READ/WRITE ONCE). Yeah, so? Complain to the compiler people for forcing us into that. > Would an API like WRITE_POINTER()/smp_store_pointer make sense, > and READ_POINTER for symmetry? No, the whole point of the exercise was to get away from the fact that dependent loads are special.

On Tue, Dec 05, 2017 at 09:51:48PM +0200, Michael S. Tsirkin wrote: > On Tue, Dec 05, 2017 at 11:33:39AM -0800, Paul E. McKenney wrote: > > On Tue, Dec 05, 2017 at 09:24:21PM +0200, Michael S. Tsirkin wrote: [ . . . ] > > > and this barrier is no longer paired with anything until > > > you realize there's a dependency barrier within READ_ONCE. > > > >

On Tue, Dec 05, 2017 at 09:51:48PM +0200, Michael S. Tsirkin wrote: > On Tue, Dec 05, 2017 at 11:33:39AM -0800, Paul E. McKenney wrote: > > On Tue, Dec 05, 2017 at 09:24:21PM +0200, Michael S. Tsirkin wrote: [ . . . ] > > > and this barrier is no longer paired with anything until > > > you realize there's a dependency barrier within READ_ONCE. > > > >

...ved READ_ONCE()? > > READ_ONCE is really all over the place (some code literally replaced all > memory accesses with READ/WRITE ONCE). > > And I also prefer smp_wmb as it seems to be cheaper on ARM. > > Would an API like WRITE_POINTER()/smp_store_pointer make sense, > and READ_POINTER for symmetry? What we do in some code is to comment the pairings, allowing the other side of the pairing to be easily located. Would that work for you? Thanx, Paul

...ved READ_ONCE()? > > READ_ONCE is really all over the place (some code literally replaced all > memory accesses with READ/WRITE ONCE). > > And I also prefer smp_wmb as it seems to be cheaper on ARM. > > Would an API like WRITE_POINTER()/smp_store_pointer make sense, > and READ_POINTER for symmetry? What we do in some code is to comment the pairings, allowing the other side of the pairing to be easily located. Would that work for you? Thanx, Paul

...new improved READ_ONCE()? > > Thanx, Paul READ_ONCE is really all over the place (some code literally replaced all memory accesses with READ/WRITE ONCE). And I also prefer smp_wmb as it seems to be cheaper on ARM. Would an API like WRITE_POINTER()/smp_store_pointer make sense, and READ_POINTER for symmetry? -- MST

...AD_ONCE is really all over the place (some code literally replaced all > > memory accesses with READ/WRITE ONCE). > > > > And I also prefer smp_wmb as it seems to be cheaper on ARM. > > > > Would an API like WRITE_POINTER()/smp_store_pointer make sense, > > and READ_POINTER for symmetry? > > What we do in some code is to comment the pairings, allowing the other > side of the pairing to be easily located. Would that work for you? > > Thanx, Paul Yes, that's exactly what I did for now. Thanks! -- MST

...rier that is paired with that barrier*. > Complain to the compiler people for forcing us into that. In some cases when you end up with all accesses going through read/write once volatile just might better. > > Would an API like WRITE_POINTER()/smp_store_pointer make sense, > > and READ_POINTER for symmetry? > > No, the whole point of the exercise was to get away from the fact that > dependent loads are special. It's a pity that dependent stores are still special. -- MST

Hi all, this is the long awaited patch series to add xen device model support in qemu; the main author is Anthony Perard. Developing this series we tried to come up with the cleanest possible solution from the qemu point of view, limiting the amount of changes to common code as much as possible. The end result still requires a couple of hooks in piix_pci but overall the impact should be very