search for: atomic_read_bit

...nd then I think this will be no better than a normal spinlock. It also doesn't seem like this algorithm even needs a seqlock, as this is just a one bit flag atomic_set_bit(using map) smp_mb__after_atomic() .. maps [...] atomic_clear_bit(using map) map = NULL; smp_mb__before_atomic(); while (atomic_read_bit(using map)) relax() Again, not clear this could be faster than a spinlock when the barriers are correct... Jason

...nd then I think this will be no better than a normal spinlock. It also doesn't seem like this algorithm even needs a seqlock, as this is just a one bit flag atomic_set_bit(using map) smp_mb__after_atomic() .. maps [...] atomic_clear_bit(using map) map = NULL; smp_mb__before_atomic(); while (atomic_read_bit(using map)) relax() Again, not clear this could be faster than a spinlock when the barriers are correct... Jason

...gt; Right, so then I tend to use spinlock first for correctness. > > >> >> atomic_set_bit(using map) >> smp_mb__after_atomic() >> .. maps [...] >> atomic_clear_bit(using map) >> >> >> map = NULL; >> smp_mb__before_atomic(); >> while (atomic_read_bit(using map)) >> ??? relax() >> >> Again, not clear this could be faster than a spinlock when the >> barriers are correct... > I've done some benchmark[1] on x86, and yes it looks even slower. It looks to me the atomic stuffs is not necessary, so in order to compare it...

...ds a seqlock, as this > is just a one bit flag Right, so then I tend to use spinlock first for correctness. > > atomic_set_bit(using map) > smp_mb__after_atomic() > .. maps [...] > atomic_clear_bit(using map) > > > map = NULL; > smp_mb__before_atomic(); > while (atomic_read_bit(using map)) > relax() > > Again, not clear this could be faster than a spinlock when the > barriers are correct... Yes, for next release we may want to use the idea from Michael like to mitigate the impact of mb. https://lwn.net/Articles/775871/ Thanks > > Jason

Hi all: This series try to fix several issues introduced by meta data accelreation series. Please review. Changes from V3: - remove the unnecessary patch Changes from V2: - use seqlck helper to synchronize MMU notifier with vhost worker Changes from V1: - try not use RCU to syncrhonize MMU notifier with vhost worker - set dirty pages after no readers - return -EAGAIN only when we find the

Hi all: This series try to fix several issues introduced by meta data accelreation series. Please review. Changes from V3: - remove the unnecessary patch Changes from V2: - use seqlck helper to synchronize MMU notifier with vhost worker Changes from V1: - try not use RCU to syncrhonize MMU notifier with vhost worker - set dirty pages after no readers - return -EAGAIN only when we find the