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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 883B1C1975A for ; Wed, 25 Mar 2020 16:41:50 +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 5BA102073E for ; Wed, 25 Mar 2020 16:41:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="RUmsAATz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5BA102073E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.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-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=wSMqSdKblEN7v9doekCOusaVwkUZVDNuntytEy+ko9I=; b=RUmsAATzS+ooX3 u7y3Vc3yVb7bmhGeELM5jQJNsvl3Mqmbwx935ZUkhjky7yuL4gvBY6LezhNehrOFGU1W/jnaxaayj kJRXcYLMUVgYk9N8HCpKdAZ4O6TjBgUVRWfhiaBqlxHFluWymI2nFyvU6PI0HxCTU+HWKdOYnqjqK vNsNgw/cVEzskMdCRlj4PFGgk3EDsXmv1+5Mg8tabz2jtTADkW9RZG+3Ns1KQXoXzws7vEkyS0cRd HfJSFPPjUa/2wycGxOsuekEho2k+PEa8kxjiQl2AN7coDqIRcBGQ4WClzozGeJ30S94Ffg/eHV5F5 MhKViFSBNEUXkCk9p4cA==; 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 1jH96D-0004Ta-9T; Wed, 25 Mar 2020 16:41:49 +0000 Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jH96B-0004TC-6K; Wed, 25 Mar 2020 16:41:47 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 813823010CF; Wed, 25 Mar 2020 17:41:44 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 665E829A7FACF; Wed, 25 Mar 2020 17:41:44 +0100 (CET) Date: Wed, 25 Mar 2020 17:41:44 +0100 From: Peter Zijlstra To: James Morse Subject: Re: [RFC PATCH v4 0/6] arm64: tlb: add support for TTL feature Message-ID: <20200325164144.GB20696@hirez.programming.kicks-ass.net> References: <20200324134534.1570-1-yezhenyu2@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: 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: mark.rutland@arm.com, catalin.marinas@arm.com, linux-mm@kvack.org, guohanjun@huawei.com, will@kernel.org, linux-arch@vger.kernel.org, yuzhao@google.com, maz@kernel.org, suzuki.poulose@arm.com, steven.price@arm.com, arm@kernel.org, Dave.Martin@arm.com, arnd@arndb.de, Zhenyu Ye , npiggin@gmail.com, zhangshaokun@hisilicon.com, broonie@kernel.org, rostedt@goodmis.org, prime.zeng@hisilicon.com, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, xiexiangyou@huawei.com, linux-kernel@vger.kernel.org, aneesh.kumar@linux.ibm.com, akpm@linux-foundation.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Mar 25, 2020 at 04:15:58PM +0000, James Morse wrote: > Hi Zhenyu, > > On 3/24/20 1:45 PM, Zhenyu Ye wrote: > > In order to reduce the cost of TLB invalidation, the ARMv8.4 TTL > > feature allows TLBs to be issued with a level allowing for quicker > > invalidation. This series provide support for this feature. > > > > Patch 1 and Patch 2 was provided by Marc on his NV series[1] patches, > > which detect the TTL feature and add __tlbi_level interface. > > How does this interact with THP? > (I don't see anything on that in the series.) > > With THP, there is no one answer to the size of mapping in a VMA. > This is a problem because the arm-arm has in "Translation table level > hints" in D5.10.2 of DDI0487E.a: > | If an incorrect value for the entry being invalidated by the > | instruction is specified in the TTL field, then no entries are > | required by the architecture to be invalidated from the TLB. > > If we get it wrong, not TLB maintenance occurs! > > Unless THP leaves its fingerprints on the vma, I think you can only do > this for VMA types that THP can't mess with. (see > transparent_hugepage_enabled()) The convention way to deal with that is to issue the TBLI for all possible sizes. Power9 has all this, please look there. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel