Re: [PATCH 8/8] blk-mq: drain I/O when all CPUs in a hctx are offline

2020-05-29 Thread Paul E. McKenney
On Fri, May 29, 2020 at 12:55:43PM -0700, Bart Van Assche wrote: > On 2020-05-29 11:13, Paul E. McKenney wrote: > > On Fri, May 29, 2020 at 11:53:15AM +0800, Ming Lei wrote: > >> Another pair is in blk_mq_get_tag(), and we expect the following two > >> memory OPs are ordered: > >> > >> 1) set bit i

Re: [PATCH 8/8] blk-mq: drain I/O when all CPUs in a hctx are offline

2020-05-29 Thread Bart Van Assche
On 2020-05-29 11:13, Paul E. McKenney wrote: > On Fri, May 29, 2020 at 11:53:15AM +0800, Ming Lei wrote: >> Another pair is in blk_mq_get_tag(), and we expect the following two >> memory OPs are ordered: >> >> 1) set bit in successful test_and_set_bit_lock(), which is called >> from sbitmap_get() >

Re: [PATCH 8/8] blk-mq: drain I/O when all CPUs in a hctx are offline

2020-05-29 Thread Paul E. McKenney
On Fri, May 29, 2020 at 11:53:15AM +0800, Ming Lei wrote: > Hi Paul, > > On Thu, May 28, 2020 at 08:07:28PM -0700, Paul E. McKenney wrote: > > On Fri, May 29, 2020 at 09:53:04AM +0800, Ming Lei wrote: > > > Hi Paul, > > > > > > Thanks for your response! > > > > > > On Thu, May 28, 2020 at 10:21:

Re: [PATCH 8/8] blk-mq: drain I/O when all CPUs in a hctx are offline

2020-05-28 Thread Ming Lei
Hi Paul, On Thu, May 28, 2020 at 08:07:28PM -0700, Paul E. McKenney wrote: > On Fri, May 29, 2020 at 09:53:04AM +0800, Ming Lei wrote: > > Hi Paul, > > > > Thanks for your response! > > > > On Thu, May 28, 2020 at 10:21:21AM -0700, Paul E. McKenney wrote: > > > On Thu, May 28, 2020 at 06:37:47AM

Re: [PATCH 8/8] blk-mq: drain I/O when all CPUs in a hctx are offline

2020-05-28 Thread Paul E. McKenney
On Fri, May 29, 2020 at 09:53:04AM +0800, Ming Lei wrote: > Hi Paul, > > Thanks for your response! > > On Thu, May 28, 2020 at 10:21:21AM -0700, Paul E. McKenney wrote: > > On Thu, May 28, 2020 at 06:37:47AM -0700, Bart Van Assche wrote: > > > On 2020-05-27 22:19, Ming Lei wrote: > > > > On Wed,

Re: [PATCH 8/8] blk-mq: drain I/O when all CPUs in a hctx are offline

2020-05-28 Thread Ming Lei
Hi Paul, Thanks for your response! On Thu, May 28, 2020 at 10:21:21AM -0700, Paul E. McKenney wrote: > On Thu, May 28, 2020 at 06:37:47AM -0700, Bart Van Assche wrote: > > On 2020-05-27 22:19, Ming Lei wrote: > > > On Wed, May 27, 2020 at 08:33:48PM -0700, Bart Van Assche wrote: > > >> My underst

Re: [PATCH 8/8] blk-mq: drain I/O when all CPUs in a hctx are offline

2020-05-28 Thread Ming Lei
On Thu, May 28, 2020 at 06:37:47AM -0700, Bart Van Assche wrote: > On 2020-05-27 22:19, Ming Lei wrote: > > On Wed, May 27, 2020 at 08:33:48PM -0700, Bart Van Assche wrote: > >> My understanding is that operations that have acquire semantics pair > >> with operations that have release semantics. I

Re: [PATCH 8/8] blk-mq: drain I/O when all CPUs in a hctx are offline

2020-05-28 Thread Paul E. McKenney
On Thu, May 28, 2020 at 06:37:47AM -0700, Bart Van Assche wrote: > On 2020-05-27 22:19, Ming Lei wrote: > > On Wed, May 27, 2020 at 08:33:48PM -0700, Bart Van Assche wrote: > >> My understanding is that operations that have acquire semantics pair > >> with operations that have release semantics. I

Re: [PATCH 8/8] blk-mq: drain I/O when all CPUs in a hctx are offline

2020-05-28 Thread Bart Van Assche
On 2020-05-27 22:19, Ming Lei wrote: > On Wed, May 27, 2020 at 08:33:48PM -0700, Bart Van Assche wrote: >> My understanding is that operations that have acquire semantics pair >> with operations that have release semantics. I haven't been able to find >> any documentation that shows that smp_mb__af

Re: [PATCH 8/8] blk-mq: drain I/O when all CPUs in a hctx are offline

2020-05-27 Thread Ming Lei
On Wed, May 27, 2020 at 08:33:48PM -0700, Bart Van Assche wrote: > On 2020-05-27 18:46, Ming Lei wrote: > > On Wed, May 27, 2020 at 04:09:19PM -0700, Bart Van Assche wrote: > >> On 2020-05-27 11:06, Christoph Hellwig wrote: > >>> --- a/block/blk-mq-tag.c > >>> +++ b/block/blk-mq-tag.c > >>> @@ -180