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 X-Spam-Level: X-Spam-Status: No, score=-1.2 required=3.0 tests=DATE_IN_PAST_03_06, DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 59DA8C432C0 for ; Sun, 1 Dec 2019 19:06:40 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2358220716 for ; Sun, 1 Dec 2019 19:06:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="ZbEM+J5b"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=jonmasters-org.20150623.gappssmtp.com header.i=@jonmasters-org.20150623.gappssmtp.com header.b="jwOVcGbn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2358220716 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=jonmasters.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=lzmHGIigO8si/9GVI812qD0WBSxxWmp3GksOVqPRRU4=; b=ZbEM+J5bHJdGyPX+7/0IQwSZB u/4GzX//dYr9EZ4jqb/ah04CGvrfapgY+4GOAYu2A1I/M4x5FPJwzO47h9K3faMGjudbdzFx0w19e kUplwN3DgMZ+27bEz5LlkjyP9C4vvfnmeZpHcu4E+ldTaQfMCCLkA1J743HO5toIHpOmNY7/mkEHA +ltzUl+KzIjuOILlSCmTXCwB24MCrO60UIWMm9qCqG8gN9HdC6KI5YL0AI/vmxkJkkNqMH1IQT5Od PrApFFzDM7PXAtYTBnq2bPeNUEvrWEVWfaMEMQ0gZ5YYZiQqXGq3SSTbg+0EQ3TWX+DOzk/i85PQe 9A0pz/wSQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ibUYE-0002GO-Cf; Sun, 01 Dec 2019 19:06:34 +0000 Received: from mail-qk1-x742.google.com ([2607:f8b0:4864:20::742]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1ibUYA-0002Fy-2Q for linux-arm-kernel@lists.infradead.org; Sun, 01 Dec 2019 19:06:31 +0000 Received: by mail-qk1-x742.google.com with SMTP id d124so15217634qke.6 for ; Sun, 01 Dec 2019 11:06:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jonmasters-org.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:organization:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=MYJMRHaiXc+sf5WEZ2y2GPKTcfT0mAf/egNeoJkGqUk=; b=jwOVcGbncaHcFffRkMA7LE9/UEhFUaIT8HSLGGQg6lzBye14j5BgANn42w4XkkyUfV ZOeYTUI0Dd3YuYKHFmy8XJ288eAiat5tF1T/Annsj7YQszO0ng4s3PnYNlcc6EvK8Mst nsUxYHAo+BA5vFB6wpkDCkxk7TWJ8NevfsWgUFUPHAht5Wo6CiF4uhiBp8edAwy1OiuX S1Jd1DrmUKk4BtedkskZETWYwSznYKzddZWM91onELxBhwwxx64JfrvTFsVTo8CLYBUB zeMcq1mqFwHppbPvN09508FJp8LjKrr8nCXj4xoCiyXtevuoR+S4h+dA+WQi+mdQEGob fBEg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:organization :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=MYJMRHaiXc+sf5WEZ2y2GPKTcfT0mAf/egNeoJkGqUk=; b=XHRr+4blTXlmfuv28RsfXMuCsajFewnoka5CwFaNL1HFj7P0hRuVfFg2onGH7OIROD s3ETvEdut9uYPgmRTk0dSG/QwryEXkBGGKqB89iL09nyOuUR985vtgyScOeSipWrXcNw hXG29aP9Qpw4IgaQ/BxP5wkzA9aKZmjIIR3dFjTXIX+Dw2LudfhP435ZO83JBbGik6Ua 3upk79W4ZPU+BpzLhEsFK2cergbbP/Z3KkrTNo1gQdMuGLt6BLzPjw2HiKZAtg/xaqQw rxrnssluzvB/Dze7JtxgauOOI60hIdVV2toCBmz4E26yCRZCWvaryrjzLeBJdblMRuja Jeog== X-Gm-Message-State: APjAAAUcuho/i1Kv7EEPyY5lZ5EoUZBRJFPEIvAoZ9hFoI3EGtOci7Ye 3HjgplgaM6BeJ/B3p9KxZqbeVA== X-Google-Smtp-Source: APXvYqxQytCbo+98XXQij13g03gGpSRogXBmEDaQ9V4RHLtJy49OLvXxEnE89dRmw7RtqJlp/u3SRg== X-Received: by 2002:a05:620a:16a4:: with SMTP id s4mr5994651qkj.488.1575227185774; Sun, 01 Dec 2019 11:06:25 -0800 (PST) Received: from independence.bos.jonmasters.org (24-148-33-89.s2391.c3-0.grn-cbr1.chi-grn.il.cable.rcncustomer.com. [24.148.33.89]) by smtp.gmail.com with ESMTPSA id k123sm6414644qkd.4.2019.12.01.11.06.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 01 Dec 2019 11:06:25 -0800 (PST) Subject: Re: [PATCH 0/2] arm64: Introduce boot parameter to disable TLB flush instruction within the same inner shareable domain To: Will Deacon , "qi.fuli@fujitsu.com" References: <20190617143255.10462-1-indou.takao@jp.fujitsu.com> <93009dbd-b31c-7364-86d2-21f0fac36676@jp.fujitsu.com> <20191101172851.GC3983@willie-the-truck> From: Jon Masters Organization: World Organi{s,z}ation of Broken Dreams Message-ID: Date: Sun, 1 Dec 2019 11:02:42 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20191101172851.GC3983@willie-the-truck> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191201_110630_173052_FED914C5 X-CRM114-Status: GOOD ( 19.91 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "tokamoto@jp.fujitsu.com" , "linux-doc@vger.kernel.org" , "peterz@infradead.org" , Catalin Marinas , Jonathan Corbet , Will Deacon , "linux-kernel@vger.kernel.org" , "maeda.naoaki@fujitsu.com" , "misono.tomohiro@fujitsu.com" , Itaru Kitayama , "linux-arm-kernel@lists.infradead.org" , "indou.takao@fujitsu.com" Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 11/1/19 1:28 PM, Will Deacon wrote: > On Fri, Nov 01, 2019 at 09:56:05AM +0000, qi.fuli@fujitsu.com wrote: >> In this thread, I explained that: >> * I found a performance problem which is caused by TLBI-is instruction. >> * The problem occurs like this: >> 1) On a core, OS tries to flush TLB using TLBI-is instruction >> 2) TLBI-is instruction causes a broadcast to all other cores, and >> each core received hard-wired signal >> 3) Each core check if there are TLB entries which have the specified >> ASID/VA (the above confuses implementation with architecture) > I think it's worth bearing in mind that I have little sympathy for the > problem that you are seeing. As far as I can tell, you've done the > following: > > 1. You designed a CPU micro-architecture that stalls whenever it receives > a TLB invalidation request. s/SPARC/Arm/ && wire in DVM > 2. You integrated said CPU design into a system where broadcast TLB > invalidation is not filtered and therefore stalls every CPU every > time that /any/ TLB invalidation is broadcast. > > 3. You deployed a mixture of Linux and jitter-sensitive software on > this system, and now you're failing to meet your performance > requirements. > > Have I got that right? > > If so, given that your CPU design isn't widely available, nobody else > appears to have made this mistake and jitter hasn't been reported as an > issue for any other systems, it's very unlikely that we're going to make > invasive upstream kernel changes to support you. I'm sorry, but all I can > suggest is that you check that your micro-architecture and performance > requirements are aligned with the design of Linux *before* building another > machine like this in future. > > I hate to be blunt, but I also don't want to waste your time. I always tried to ask nicely for the above to be heeded. There's a difference between "hi, our implementation doesn't scale, and here's why" vs "there's a problem with all TLBIs...". There isn't. The problem is the implementation and that should have been called out first thing. Jon. -- Computer Architect _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel