On Wed, Jan 19, 2022 at 02:08:48PM +0000, Praveen Kannoju wrote: > From: Jason Gunthorpe [mailto:jgg@xxxxxxxx] > Sent: 19 January 2022 06:47 PM > To: Praveen Kannoju <praveen.kannoju@xxxxxxxxxx> > Cc: Leon Romanovsky <leon@xxxxxxxxxx>; Santosh Shilimkar <santosh.shilimkar@xxxxxxxxxx>; David S . Miller <davem@xxxxxxxxxxxxx>; kuba@xxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx; rds-devel@xxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Rama Nichanamatlu <rama.nichanamatlu@xxxxxxxxxx>; Rajesh Sivaramasubramaniom <rajesh.sivaramasubramaniom@xxxxxxxxxx> > Subject: Re: [PATCH RFC] rds: ib: Reduce the contention caused by the asynchronous workers to flush the mr pool > > On Wed, Jan 19, 2022 at 01:12:29PM +0000, Praveen Kannoju wrote: > > > Yes, we are using the barriers. I was justifying the usage of > > smp_rmb() and smp_wmb() over smp_load_acquire() and > > smp_store_release() in the patch. > > You failed to justify it. > > Jason > > Apologies, if my earlier point is not clear, Jason. > Let me reframe: > > 1. The introduced bool variable "flush_ongoing", is being accessed only in the function "rds_ib_free_mr" while spawning asynchronous workers. > > 2. The ordering guaranteed by smp_rmb() and smp_wmb() would be > sufficient for such simple usage and hence we did not use > smp_load_acquire() and smp_store_release(). Again you haven't defined why these barriers are any differnet from acquire/release or even *what they are doing* Jason
