search for: barriers

...O at all. Of course it's wrong in the sense that it's suboptimal. What we would really like is to have, on UP, exactly the same barrier as on SMP. This is because a UP guest can run on an SMP host. But Linux doesn't provide this ability: if CONFIG_SMP is not defined is optimizes most barriers out to a compiler barrier. Consider for example x86: what we want is xchg (NOT mfence - there's no real IO going on here - just switching out of the VM - more like a function call really) but if built without CONFIG_SMP smp_store_mb does not include this. Virt in general is probably the only...

...O at all. Of course it's wrong in the sense that it's suboptimal. What we would really like is to have, on UP, exactly the same barrier as on SMP. This is because a UP guest can run on an SMP host. But Linux doesn't provide this ability: if CONFIG_SMP is not defined is optimizes most barriers out to a compiler barrier. Consider for example x86: what we want is xchg (NOT mfence - there's no real IO going on here - just switching out of the VM - more like a function call really) but if built without CONFIG_SMP smp_store_mb does not include this. Virt in general is probably the only...

...O at all. Of course it's wrong in the sense that it's suboptimal. What we would really like is to have, on UP, exactly the same barrier as on SMP. This is because a UP guest can run on an SMP host. But Linux doesn't provide this ability: if CONFIG_SMP is not defined is optimizes most barriers out to a compiler barrier. Consider for example x86: what we want is xchg (NOT mfence - there's no real IO going on here - just switching out of the VM - more like a function call really) but if built without CONFIG_SMP smp_store_mb does not include this. Virt in general is probably the only...

...O at all. Of course it's wrong in the sense that it's suboptimal. What we would really like is to have, on UP, exactly the same barrier as on SMP. This is because a UP guest can run on an SMP host. But Linux doesn't provide this ability: if CONFIG_SMP is not defined is optimizes most barriers out to a compiler barrier. Consider for example x86: what we want is xchg (NOT mfence - there's no real IO going on here - just switching out of the VM - more like a function call really) but if built without CONFIG_SMP smp_store_mb does not include this. Virt in general is probably the only...

...afd2ff9b7e1b367172f18ba7f693dfb62bdcb2dc: Linux 4.4 (2016-01-10 15:01:32 -0800) are available in the git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git tags/for_linus for you to fetch changes up to 43e361f23c49dbddf74f56ddf6cdd85c5dbff6da: checkpatch: add virt barriers (2016-01-12 20:47:08 +0200) ---------------------------------------------------------------- virtio: barrier rework+fixes This adds a new kind of barrier, and reworks virtio and xen to use it. Plus some fixes here and there. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> ----------...

...afd2ff9b7e1b367172f18ba7f693dfb62bdcb2dc: Linux 4.4 (2016-01-10 15:01:32 -0800) are available in the git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git tags/for_linus for you to fetch changes up to 43e361f23c49dbddf74f56ddf6cdd85c5dbff6da: checkpatch: add virt barriers (2016-01-12 20:47:08 +0200) ---------------------------------------------------------------- virtio: barrier rework+fixes This adds a new kind of barrier, and reworks virtio and xen to use it. Plus some fixes here and there. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> ----------...

Changes since v2: - extended checkpatch tests for barriers, and added patches teaching it to warn about incorrect usage of barriers (__smp_xxx barriers are for use by asm-generic code only), should help prevent misuse by arch code to address comments by Russell King - patched more instances of xen to use virt_ barriers as suggested by Stefano Stabel...

Changes since v2: - extended checkpatch tests for barriers, and added patches teaching it to warn about incorrect usage of barriers (__smp_xxx barriers are for use by asm-generic code only), should help prevent misuse by arch code to address comments by Russell King - patched more instances of xen to use virt_ barriers as suggested by Stefano Stabel...

Hi Michael, On Thu, Dec 31, 2015 at 09:08:22PM +0200, Michael S. Tsirkin wrote: > This defines __smp_xxx barriers for metag, > for use by virtualization. > > smp_xxx barriers are removed as they are > defined correctly by asm-generic/barriers.h > > Note: as __smp_XX macros should not depend on CONFIG_SMP, they can not > use the existing fence() macro since that is defined differently bet...

Hi Michael, On Thu, Dec 31, 2015 at 09:08:22PM +0200, Michael S. Tsirkin wrote: > This defines __smp_xxx barriers for metag, > for use by virtualization. > > smp_xxx barriers are removed as they are > defined correctly by asm-generic/barriers.h > > Note: as __smp_XX macros should not depend on CONFIG_SMP, they can not > use the existing fence() macro since that is defined differently bet...

...t; Linux 4.4 (2016-01-10 15:01:32 -0800) > > are available in the git repository at: > > git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git tags/for_linus > > for you to fetch changes up to 43e361f23c49dbddf74f56ddf6cdd85c5dbff6da: > > checkpatch: add virt barriers (2016-01-12 20:47:08 +0200) > > ---------------------------------------------------------------- > virtio: barrier rework+fixes > > This adds a new kind of barrier, and reworks virtio and xen > to use it. > Plus some fixes here and there. > > Signed-off-by: Michael S....

As part of memory barrier cleanup, this patchset extends checkpatch to make it easier to stop incorrect memory barrier usage. This replaces the checkpatch patches in my series arch: barrier cleanup + barriers for virt and will be included in the pull request including the series. changes from v3: rename smp_barrier_stems to barrier_stems as suggested by Julian Calaby. add (?: ... ) around a variable in regexp, in case we change the value later so that it matters. changes from v2: address comments...

As part of memory barrier cleanup, this patchset extends checkpatch to make it easier to stop incorrect memory barrier usage. This replaces the checkpatch patches in my series arch: barrier cleanup + barriers for virt and will be included in the pull request including the series. changes from v3: rename smp_barrier_stems to barrier_stems as suggested by Julian Calaby. add (?: ... ) around a variable in regexp, in case we change the value later so that it matters. changes from v2: address comments...

On Sun, Jan 10, 2016 at 04:16:32PM +0200, Michael S. Tsirkin wrote: > From: Davidlohr Bueso <dave at stgolabs.net> > > With commit b92b8b35a2e ("locking/arch: Rename set_mb() to smp_store_mb()") > it was made clear that the context of this call (and thus set_mb) > is strictly for CPU ordering, as opposed to IO. As such all archs > should use the smp variant of

On Sun, Jan 10, 2016 at 04:16:32PM +0200, Michael S. Tsirkin wrote: > From: Davidlohr Bueso <dave at stgolabs.net> > > With commit b92b8b35a2e ("locking/arch: Rename set_mb() to smp_store_mb()") > it was made clear that the context of this call (and thus set_mb) > is strictly for CPU ordering, as opposed to IO. As such all archs > should use the smp variant of

As part of memory barrier cleanup, this patchset extends checkpatch to make it easier to stop incorrect memory barrier usage. This applies on top of my series arch: barrier cleanup + barriers for virt and will be included in the next version of the series. Michael S. Tsirkin (3): checkpatch.pl: add missing memory barriers checkpatch: check for __smp outside barrier.h checkpatch: add virt barriers scripts/checkpatch.pl | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+)...

As part of memory barrier cleanup, this patchset extends checkpatch to make it easier to stop incorrect memory barrier usage. This applies on top of my series arch: barrier cleanup + barriers for virt and will be included in the next version of the series. Michael S. Tsirkin (3): checkpatch.pl: add missing memory barriers checkpatch: check for __smp outside barrier.h checkpatch: add virt barriers scripts/checkpatch.pl | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+)...

As part of memory barrier cleanup, this patchset extends checkpatch to make it easier to stop incorrect memory barrier usage. This applies on top of my series arch: barrier cleanup + barriers for virt and will be included in the next version of the series. Changes from v2: catch optional\s* before () in barriers rewrite using qr{} instead of map Michael S. Tsirkin (3): checkpatch.pl: add missing memory barriers checkpatch: check for __smp outside barrier.h checkpatch: add virt...

As part of memory barrier cleanup, this patchset extends checkpatch to make it easier to stop incorrect memory barrier usage. This applies on top of my series arch: barrier cleanup + barriers for virt and will be included in the next version of the series. Changes from v2: catch optional\s* before () in barriers rewrite using qr{} instead of map Michael S. Tsirkin (3): checkpatch.pl: add missing memory barriers checkpatch: check for __smp outside barrier.h checkpatch: add virt...

On Thu, Dec 31, 2015 at 09:08:38PM +0200, Michael S. Tsirkin wrote: > This defines __smp_xxx barriers for s390, > for use by virtualization. > > Some smp_xxx barriers are removed as they are > defined correctly by asm-generic/barriers.h > > Note: smp_mb, smp_rmb and smp_wmb are defined as full barriers > unconditionally on this architecture. > > Signed-off-by: Michael...