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 D344BC433FE for ; Mon, 17 Jan 2022 14:35:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234552AbiAQOfH (ORCPT ); Mon, 17 Jan 2022 09:35:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39490 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234441AbiAQOfH (ORCPT ); Mon, 17 Jan 2022 09:35:07 -0500 Received: from mail-qk1-x732.google.com (mail-qk1-x732.google.com [IPv6:2607:f8b0:4864:20::732]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 83D39C061574 for ; Mon, 17 Jan 2022 06:35:06 -0800 (PST) Received: by mail-qk1-x732.google.com with SMTP id u3so9674337qku.1 for ; Mon, 17 Jan 2022 06:35:06 -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=LKnEDfDOHP1Gip6gRtRx9OLQcL2NYzw8mzTYclLdF4s=; b=aC1EmsTewa52sMnAPMz6IQu008I9AIA+izvrBSne4wMNuUEfeyVQyEZoqhjSvFxt69 zflOIjtNMu5Bx2dT4DYPPGjAvT4SoahXFZCL0UE4YMSnglPg3iRbiuzMIuW217NGK70g MufhzdXEGoR877oIRVlxS0CtcPvc2Cf4QTC9hkdAntNYSpzYblIJVftKJ2m4Fm+K0Rl6 hmTomYyfM+TBTCs4Pd6xtw+XbsdbShU/YWqGWqybQBd6Z2SXJ4wHm4vT8y8Oown3D9Hc 3eWJxH3N5Cjnh+wo/zhbQifR5rNWNqvroawQJfzXX0FRlDFDZ3FXjHSY+Od6FJAx/vw1 M8EA== 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=LKnEDfDOHP1Gip6gRtRx9OLQcL2NYzw8mzTYclLdF4s=; b=GrvUvN7AAcWJIbmTUNo2Tc5+8+xOHppzKEI/TC6FtvKKUKVkEdmWJFeD/KDS1eotN0 93SuSeJ6sCiDuuAGI77wadAyq/1vx6Ph2AoATwurAclMQ8ROiFcmX3bCzI6d4Rkh3dAu wxwH0tYGlgjfmMjVIXb8vuNou3TgltiGhjm5FtCrJVHTKGfI1Ix53G/UO4lxgSdsu/PI AnqkFk/2AhAEzOinwDkfY/KH4+hoiPnykZQTvQzB8LSjl+ojAzJxCQ8WRBTyiItD1zk6 KTAlPPidIPs9CkCJGGygLbkCB2DlYTRuSFMe1SxgWjshhDse4LZtxErf3/oiIapaHzAl tawA== X-Gm-Message-State: AOAM532hfJXLmGpEzFX1mYrPpRZXiBe+BaeG3TAFDfG2Wi2+2yX/3wUd HYMZyLLaQ/BiKjXNDZPmnEQ9Og== X-Google-Smtp-Source: ABdhPJzriuj66plk0X5JWi15JmxxQS+GXJ2UdCpUt1IP9QUW1YzM4Otm0s55qIPg7xqowu6Zpf7P0w== X-Received: by 2002:a37:9f53:: with SMTP id i80mr10948521qke.17.1642430105691; Mon, 17 Jan 2022 06:35:05 -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 i7sm9365037qkn.0.2022.01.17.06.35.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Jan 2022 06:35:05 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1n9T68-000JB4-7D; Mon, 17 Jan 2022 10:35:04 -0400 Date: Mon, 17 Jan 2022 10:35:04 -0400 From: Jason Gunthorpe To: Haakon Bugge Cc: Bob Pearson , "yangx.jy@fujitsu.com" , Leon Romanovsky , OFED mailing list Subject: Re: [rdma-core PATCH] providers/rxe: Replace '%' with '&' in check_qp_queue_full() Message-ID: <20220117143504.GA8034@ziepe.ca> References: <20220111014145.2374669-1-yangx.jy@fujitsu.com> <61DCEA00.1030002@fujitsu.com> <326487d9-74cc-185e-1790-90730425057a@gmail.com> <5A111A92-427C-4FE1-BDA1-6E8877350D20@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5A111A92-427C-4FE1-BDA1-6E8877350D20@oracle.com> Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Mon, Jan 17, 2022 at 11:12:12AM +0000, Haakon Bugge wrote: > > The way these queues work they can only hold 2^n - 1 entries. The > > reason for this is to distinguish empty and full. > > You can simply mitigate that by having free-running counters, right? That is generally the best design, with the cost of doing the & on every use of queue data vs only on ++ Jason