From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0814EC433FE for ; Wed, 19 Jan 2022 13:04:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354669AbiASNEy (ORCPT ); Wed, 19 Jan 2022 08:04:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354561AbiASNEw (ORCPT ); Wed, 19 Jan 2022 08:04:52 -0500 Received: from mail-qk1-x730.google.com (mail-qk1-x730.google.com [IPv6:2607:f8b0:4864:20::730]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95C8CC061574 for ; Wed, 19 Jan 2022 05:04:52 -0800 (PST) Received: by mail-qk1-x730.google.com with SMTP id t1so2538538qkt.11 for ; Wed, 19 Jan 2022 05:04:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=PdBsLwTPPCRnlF0tAGck2uC9WYpIzKTvIZtFGv5axas=; b=id2q0sYnHRhFNE9VD9xueoZt/qcezsUBeZvxMkZqSpN6A21B1azzpRyW7wgh4WjfiK hWCfpAzLanOMfrKhduRcgE1Qru2f3jbOzbPV/YlF2ynDNO6GG5FrxtAmDqKFcvTLacg0 quqzUTMC/M7z2d3BrugWX/AAfPxHRmLksobHfRXyR3ZLBAeT9dqRjkECzPIzC3RpoAU7 HVM291if145vJdGYmP0D9AU4bBbiPb8ybnEpn9Li+DTcwBFOpCA0kkuMVAIJE/UQ3thI 87k6B1OkcXdfhY9iKZuBKJJfUeMxb5TRggbPHSjbsPstzr1wQHtWaF3SY408Zneh01zb ZPsg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=PdBsLwTPPCRnlF0tAGck2uC9WYpIzKTvIZtFGv5axas=; b=bUE1B2/BXTtPVLHA6i7dX6Kc/7TwthpudcubygtC59yGRL6hsbxu34lihM/S+q1lSo EWZvsCVHI9fE6hmAt6+R+sqX9IQ/Dd9zF/N7eea1MPJTD6sG0/JQYMdagZUzmpFTNLQl BmviwAUFZ6oE34Ml5YkCWeyEH0d03gs6UT8Mwv3qOv+4RH7C/rYH2L17wv+DmWU/q+CO uZxjl4SyXkMJld7Bh5H6K49EDSX31v1LvA5AOBVAkokhXNIASirp+I2OF785v5dbDFVQ mJhS63CFunORyejcf3jeJLTPYX9c2AYGFiTM7sN2thhZKYzv8wIV8Hf7nCzYJ6rD/+bw S8Xw== X-Gm-Message-State: AOAM5316I13Bdi1sKp415EUyiAY/FBBDmmap+oF3FKZFuUKZo0vNVL2X FJLD8m4wij8tsRbHYez86fg7NQ== X-Google-Smtp-Source: ABdhPJwP2OqdieY5HOVRhMknqsPZXcnogOqeLFHeDfvJHpNa6Geya14CaF6r2cZylDrXsIK3Raih2g== X-Received: by 2002:a05:620a:12f6:: with SMTP id f22mr21806061qkl.652.1642597491724; Wed, 19 Jan 2022 05:04:51 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-162-113-129.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.113.129]) by smtp.gmail.com with ESMTPSA id de3sm2993864qkb.79.2022.01.19.05.04.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Jan 2022 05:04:51 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1nAAdu-001IJC-DT; Wed, 19 Jan 2022 09:04:50 -0400 Date: Wed, 19 Jan 2022 09:04:50 -0400 From: Jason Gunthorpe To: Praveen Kannoju Cc: Leon Romanovsky , Santosh Shilimkar , "David S . Miller" , "kuba@kernel.org" , "netdev@vger.kernel.org" , "linux-rdma@vger.kernel.org" , "rds-devel@oss.oracle.com" , "linux-kernel@vger.kernel.org" , Rama Nichanamatlu , Rajesh Sivaramasubramaniom Subject: Re: [PATCH RFC] rds: ib: Reduce the contention caused by the asynchronous workers to flush the mr pool Message-ID: <20220119130450.GJ8034@ziepe.ca> References: <1642517238-9912-1-git-send-email-praveen.kannoju@oracle.com> <53D98F26-FC52-4F3E-9700-ED0312756785@oracle.com> <20220118191754.GG8034@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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