From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 5B436A046B for ; Sat, 24 Aug 2019 20:20:34 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id DE6CD1BFCE; Sat, 24 Aug 2019 20:20:32 +0200 (CEST) Received: from mail-io1-f68.google.com (mail-io1-f68.google.com [209.85.166.68]) by dpdk.org (Postfix) with ESMTP id BFE531BFCD for ; Sat, 24 Aug 2019 20:20:30 +0200 (CEST) Received: by mail-io1-f68.google.com with SMTP id l7so27801492ioj.6 for ; Sat, 24 Aug 2019 11:20:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=Bf4k46Je/xoDcEmdo2r7KuL8dViyXPnZls4UdBhLmSI=; b=aBBWDm9fbZ/begVYkUWOWXXolWinYKCvhqSqYeNsLjH9fLUNxgmlbdNn6nFRBdSrcI l1pzbZoA3+xrkoG45OsFxkG0WHRtHWdKf8CaYBiIZslPrMmMGPtdIFeDp9ijgSSEUAiN yxZ5J2rq7xxNHCoCBUHeHPvdqb8SXYRXIRotiK2iwqcuGicSXlZYbrilrYQXI85AC0sZ AHANrhsWDINSJ85Wb8TlzP5A/HI5H3FUp0AlEgLFzl7nxb7H/tysUaVzSXp6VEjfzPJu l2HpoUgtNUpZ6IvlJncfF2bejfPWqtc5tAPZkV7YXJs34Ra+KDdQHuCBrTygGYi3Mner jXZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Bf4k46Je/xoDcEmdo2r7KuL8dViyXPnZls4UdBhLmSI=; b=SN02lWI7DHv2oSqAmf7vhDNEQtAPeg4aiKhFlb5ldmaeNS2kvpbIngz0ft5U+cFyNl fW1DzpN5mUl68fFsqnCIARDp0qXHg8gfrwqeSl4qxDGwtWo4/RHHbsFh9tpg0dZGeeCQ HI22+gaYFm1IMRueLQFT5ub8MmiXIrOqNtllazl7K914GYk+XlSIHD+ymPuos4mTm/IJ ImJiSrXNHbo8qXPbKAz6tl6ILCWNc3UCkcbxv1GGR2uIYgqKtiIzPR6eYVodC+FcVVcs lMt+KSU8iE8d9zsj90OlLcljrY4AV2ZIb1q3nBnOjohiNf9l2mYuW0lu7Hvv3NvEKr3Z 9dXg== X-Gm-Message-State: APjAAAXvfZUetqarL25Fe9cmCkGFuDpUE/oDE/2wX4K+Cje7gGIBFg3E QsEAXfDKfM8KbG1DYHNBuvg8zQ== X-Google-Smtp-Source: APXvYqy7G/mnzuWdxXbLZmS0TLXFrQcFRY+T6b602Pg06B9+DEMMwNxrZSO5i5kxXDHuFO2w/tNOEQ== X-Received: by 2002:a5d:97cf:: with SMTP id k15mr14984531ios.151.1566670829830; Sat, 24 Aug 2019 11:20:29 -0700 (PDT) Received: from xps13.local.tld (cpe-67-255-90-149.maine.res.rr.com. [67.255.90.149]) by smtp.gmail.com with ESMTPSA id e19sm4775735iom.57.2019.08.24.11.20.28 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sat, 24 Aug 2019 11:20:29 -0700 (PDT) Date: Thu, 22 Aug 2019 21:23:07 -0400 From: Stephen Hemminger To: Ruifeng Wang Cc: bruce.richardson@intel.com, vladimir.medvedkin@intel.com, olivier.matz@6wind.com, dev@dpdk.org, honnappa.nagarahalli@arm.com, dharmik.thakkar@arm.com, nd@arm.com Message-ID: <20190822212258.1a8f7292@xps13> In-Reply-To: <20190822063457.41596-4-ruifeng.wang@arm.com> References: <20190822063457.41596-1-ruifeng.wang@arm.com> <20190822063457.41596-4-ruifeng.wang@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [RFC PATCH 3/3] lib/lpm: integrate RCU QSBR X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Thu, 22 Aug 2019 14:34:57 +0800 Ruifeng Wang wrote: > Currently, the tbl8 group is freed even though the readers might be > using the tbl8 group entries. The freed tbl8 group can be reallocated > quickly. This results in incorrect lookup results. > > RCU QSBR process is integrated for safe tbl8 group reclaim. > Refer to RCU documentation to understand various aspects of > integrating RCU library into other libraries. > > Signed-off-by: Ruifeng Wang > Reviewed-by: Honnappa Nagarahalli > Reviewed-by: Gavin Hu Having RCU in LPM is a good idea but difficult to find out how to do it in DPDK. Not everyone wants to use RCU, so making a required part of how LPM is used will impact users. Also, it looks like DPDK RCU lacks a good generic way to handle deferred free. Having to introduce a ring to handle is adding more complexity when a generic solution would be better (see userspace RCU library for example). Other parts of DPDK would benefit if deferred free was done better.