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 C19DDA052E; Mon, 9 Mar 2020 09:56:07 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 8F6641BECF; Mon, 9 Mar 2020 09:56:07 +0100 (CET) Received: from mail-qv1-f67.google.com (mail-qv1-f67.google.com [209.85.219.67]) by dpdk.org (Postfix) with ESMTP id 71014FEB for ; Mon, 9 Mar 2020 09:56:06 +0100 (CET) Received: by mail-qv1-f67.google.com with SMTP id r15so4005169qve.3 for ; Mon, 09 Mar 2020 01:56:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=LJ8xxFvW0FhzhwcZHhfKM1MhG3J+0DICnJAHjBx93O0=; b=QfnPo7J4SJDZ8rvOHLedy+u+3+igdm41CfSmoKN0xVuInRkq30H76q7DoMX+oTZhSb SlYPhk3HpxVygdqwLuuLGG8FEQ63/4yH6v+9rS7/UZW61RxmmZCsScQKsln7ftxKj9l3 v7gTF4eelPXDpz73bBHA2QmWfACywXC79CTJBvx197Jhv1Ng8San12WjQO4HL1gEEHHr JLYgTMLjCDvmXu/RyHLUVoIiry36wWbgcmuRUGq2NN4pbXC2F0THTU+TMguADpe8jRxp WhaORM+iEtkp0ZtxYgAf6SFOxBdtQV0v8WLuqDaV5TzhYIkaqUEPwWPOkU1E22y6x/I/ mQIQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=LJ8xxFvW0FhzhwcZHhfKM1MhG3J+0DICnJAHjBx93O0=; b=RFAV2sct24bO7mV0vDp3xi4LcaRYEn969FD9FgSFTeuUWLX3LyPgZlqi7cj/drdLfH 5uo41vR5AJHwXNo1+yMMP+MHFkkB9i4MFQKmvDELULiZnfuEIefrRX2P58UYxpkIXeO6 z1AXKheQpp0AKHCvY3QrHa8cNkWnussE8mL5Yu4gwy4qUY0FyPof+VvWpVTlRr69XU4n hXCM+VGvrjwcOSQnhPYM/fkc/yBz+Lar4oymat9CfsTIhQ22fbjRvxkwgO5Pc360GYYR AenkeX3wUlyGOyw3MF+/DP8rJ05GB4t2lHsuQpVOlihU7aOM7jnYO6AqLlmTgkFTy0kt TdEw== X-Gm-Message-State: ANhLgQ1gaDjMgaHxUZKaRqpFtEsTbplopLoE1OVWF3f2kVpIAjee9pox LcGYUuqJjixY3tVf9Ym0IgqdGeZwD72eh2qm7N8= X-Google-Smtp-Source: ADFU+vthH9ckpCmPX3WsWQNs8hF7a+cmq0hgYxf23v+yQ2hsD96w7+0X4i7e8vAroSVDljCUnoU33JIZcSHzYkmTvV8= X-Received: by 2002:a05:6214:17c3:: with SMTP id cu3mr8313328qvb.135.1583744165684; Mon, 09 Mar 2020 01:56:05 -0700 (PDT) MIME-Version: 1.0 References: <1583114253-15345-1-git-send-email-xiangxia.m.yue@gmail.com> <1583501776-9958-1-git-send-email-xiangxia.m.yue@gmail.com> <7420c590-4906-34e2-b0b8-d412df9005c8@solarflare.com> <20200309082705.GM13822@platinum> In-Reply-To: <20200309082705.GM13822@platinum> From: Tonghao Zhang Date: Mon, 9 Mar 2020 16:55:28 +0800 Message-ID: To: Olivier Matz Cc: Andrew Rybchenko , Jerin Jacob , dpdk-dev , Gage Eads , "Artem V. Andreev" , Jerin Jacob , Nithin Dabilpuram , Vamsi Attunuru , Hemant Agrawal Content-Type: text/plain; charset="UTF-8" Subject: Re: [dpdk-dev] [PATCH dpdk-dev v3] mempool: sort the rte_mempool_ops by name 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 Mon, Mar 9, 2020 at 4:27 PM Olivier Matz wrote: > > Hi, > > On Mon, Mar 09, 2020 at 11:01:25AM +0800, Tonghao Zhang wrote: > > On Sat, Mar 7, 2020 at 8:54 PM Andrew Rybchenko > > wrote: > > > > > > On 3/7/20 3:51 PM, Andrew Rybchenko wrote: > > > > On 3/6/20 4:37 PM, Jerin Jacob wrote: > > > >> On Fri, Mar 6, 2020 at 7:06 PM wrote: > > > >>> From: Tonghao Zhang > > > >>> > > > >>> The order of mempool initiation affects mempool index in the > > > >>> rte_mempool_ops_table. For example, when building APPs with: > > > >>> > > > >>> $ gcc -lrte_mempool_bucket -lrte_mempool_ring ... > > > >>> > > > >>> The "bucket" mempool will be registered firstly, and its index > > > >>> in table is 0 while the index of "ring" mempool is 1. DPDK > > > >>> uses the mk/rte.app.mk to build APPs, and others, for example, > > > >>> Open vSwitch, use the libdpdk.a or libdpdk.so to build it. > > > >>> The mempool lib linked in dpdk and Open vSwitch is different. > > > >>> > > > >>> The mempool can be used between primary and secondary process, > > > >>> such as dpdk-pdump and pdump-pmd/Open vSwitch(pdump enabled). > > > >>> There will be a crash because dpdk-pdump creates the "ring_mp_mc" > > > >>> ring which index in table is 0, but the index of "bucket" ring > > > >>> is 0 in Open vSwitch. If Open vSwitch use the index 0 to get > > > >>> mempool ops and malloc memory from mempool. The crash will occur: > > > >>> > > > >>> bucket_dequeue (access null and crash) > > > >>> rte_mempool_get_ops (should get "ring_mp_mc", > > > >>> but get "bucket" mempool) > > > >>> rte_mempool_ops_dequeue_bulk > > > >>> ... > > > >>> rte_pktmbuf_alloc > > > >>> rte_pktmbuf_copy > > > >>> pdump_copy > > > >>> pdump_rx > > > >>> rte_eth_rx_burst > > > >>> > > > >>> To avoid the crash, there are some solution: > > > >>> * constructor priority: Different mempool uses different > > > >>> priority in RTE_INIT, but it's not easy to maintain. > > > >>> > > > >>> * change mk/rte.app.mk: Change the order in mk/rte.app.mk to > > > >>> be same as libdpdk.a/libdpdk.so, but when adding a new mempool > > > >>> driver in future, we must make sure the order. > > > >>> > > > >>> * register mempool orderly: Sort the mempool when registering, > > > >>> so the lib linked will not affect the index in mempool table. > > > >>> > > > >>> Signed-off-by: Tonghao Zhang > > > >>> Acked-by: Olivier Matz > > > >> Acked-by: Jerin Jacob > > > > > > > > The patch is OK, but the fact that ops index changes during > > > > mempool driver lifetime is frightening. In fact it breaks > > > > rte_mempool_register_ops() return value semantics (read > > > > as API break). The return value is not used in DPDK, but it > > > > is a public function. If I'm not mistaken it should be taken > > > > into account. > > Good points. > > The fact that the ops index changes during mempool driver lifetime is > indeed frightening, especially knowning that this is a dynamic > registration that could happen at any moment in the life of the > application. Also, breaking the ABI is not desirable. That solution is better. > Let me try to propose something else to solve your issue: > > 1/ At init, the primary process allocates a struct in shared memory > (named memzone): > > struct rte_mempool_shared_ops { > size_t num_mempool_ops; > struct { > char name[RTE_MEMPOOL_OPS_NAMESIZE]; > } mempool_ops[RTE_MEMPOOL_MAX_OPS_IDX]; > char *mempool_ops_name[RTE_MEMPOOL_MAX_OPS_IDX]; > rte_spinlock_t mempool; > } > > 2/ When we register a mempool ops, we first get a name and id from the > shared struct: with the lock held, lookup for the registered name and > return its index, else get the last id and copy the name in the struct. > > 3/ Then do as before (in the per-process global table), except that we > reuse the registered id. > > We can remove the num_ops field from rte_mempool_ops_table. > > Thoughts? > > > > Yes, should update the doc: how about this: > > > > diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h > > index c90cf31..5a9c8a7 100644 > > --- a/lib/librte_mempool/rte_mempool.h > > +++ b/lib/librte_mempool/rte_mempool.h > > @@ -904,7 +904,9 @@ int rte_mempool_ops_get_info(const struct rte_mempool *mp, > > * @param ops > > * Pointer to an ops structure to register. > > * @return > > - * - >=0: Success; return the index of the ops struct in the table. > > + * - >=0: Success; return the index of the last ops struct in the table. > > + * The number of the ops struct registered is equal to index > > + * returned + 1. > > * - -EINVAL - some missing callbacks while registering ops struct. > > * - -ENOSPC - the maximum number of ops structs has been reached. > > */ > > diff --git a/lib/librte_mempool/rte_mempool_ops.c > > b/lib/librte_mempool/rte_mempool_ops.c > > index b0da096..053f340 100644 > > --- a/lib/librte_mempool/rte_mempool_ops.c > > +++ b/lib/librte_mempool/rte_mempool_ops.c > > @@ -26,7 +26,11 @@ struct rte_mempool_ops_table rte_mempool_ops_table = { > > return strcmp(m_a->name, m_b->name); > > } > > > > -/* add a new ops struct in rte_mempool_ops_table, return its index. */ > > +/* > > + * add a new ops struct in rte_mempool_ops_table. > > + * on success, return the index of the last ops > > + * struct in the table. > > + */ > > int > > rte_mempool_register_ops(const struct rte_mempool_ops *h) > > { > > > > Also I remember patches which warn about above behaviour > > > > in documentation. If behaviour changes, corresponding > > > > documentation must be updated. > > > > > > One more point. If the patch is finally accepted it definitely > > > deserves few lines in release notes. > > OK, a separate patch should be sent before DPDK 20.05 release ? > > > > > > > > > -- > > Thanks, > > Tonghao -- Thanks, Tonghao