-----Original Message----- From: Jason Gunthorpe [mailto:jgg@xxxxxxxx] Sent: 19 January 2022 06:35 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 11:46:16AM +0000, Praveen Kannoju wrote: > 6. Jason, the only function "rds_ib_free_mr" which accesses the > introduced bool variable "flush_ongoing" to spawn a flush worker does > not crucially impact the availability of MR's, because the flush > happens from allocation path as well when necessary. Hence the > Load-store ordering is not essentially needed here, because of which > we chose smp_rmb() and smp_wmb() over smp_load_acquire() and > smp_store_release(). That seems like a confusing statement, you added barriers which do the same things as acquire/release then say you didn't need acquire release? I think this is using barriers wrong. Jason Jason, 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.
