From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 2278A46B3A; Thu, 10 Jul 2025 16:37:50 +0200 (CEST) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id A1D5E402AE; Thu, 10 Jul 2025 16:37:49 +0200 (CEST) Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by mails.dpdk.org (Postfix) with ESMTP id 28661400D6 for ; Thu, 10 Jul 2025 16:37:48 +0200 (CEST) Received: by linux.microsoft.com (Postfix, from userid 1213) id 4AA11211426E; Thu, 10 Jul 2025 07:37:47 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 4AA11211426E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1752158267; bh=PNrmDwQTaQrFPBE1FdUeMkk43cj7ExMeCdfLku6HI2w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UVpdlUn+21csE+1sWMy/AxD3qc0Tf9+s0q4MNdSj2UdrabS0tyVkLSYHYD8J80ywh yuvzCyUrYoH8LuHmMq7GfzhGH6bjIwQSgxxa3HFHOfQL/UecYMvGuFGahHIouKql14 bgCGpPdxNmYA/hlRAmHf2yOR9Tsy+Ae6R5KhGneI= Date: Thu, 10 Jul 2025 07:37:47 -0700 From: Andre Muezerie To: Thomas Monjalon Cc: dev@dpdk.org, Konstantin Ananyev , David Marchand , Bruce Richardson , honnappa.nagarahalli@arm.com Subject: Re: [PATCH] rcu: add deprecation notice about limit on defer queue element size Message-ID: <20250710143747.GA24344@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net> References: <1747957021-2581-1-git-send-email-andremue@linux.microsoft.com> <4620749.daG60p0z9X@thomas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4620749.daG60p0z9X@thomas> User-Agent: Mutt/1.5.21 (2010-09-15) X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On Tue, Jul 01, 2025 at 04:17:20PM +0200, Thomas Monjalon wrote: > 23/05/2025 01:37, Andre Muezerie: > > The functions rte_rcu_qsbr_dq_create and rte_rcu_qsbr_dq_reclaim establish > > no limit on the size of each element in the defer queue. > > Very good, we need more unlimited API in DPDK. > > > With DPDK 25.11 a hard limit will be set (``RTE_QSBR_ESIZE_MAX``). > > I think it is a step in the wrong direction. > I prefer having no limit. > > > This will allow fixed C arrays to be used in the functions' implementations, > > avoiding VLAs and use of alloca(). > > I don't understand this justification. > Why trying to remove the 2 alloca() in the lib RCU? > Only because other developer expressed concerns that using alloca() allows ill-intended callers to cause a stack overflow. I personally also prefer to have no hardcoded limits.