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=-4.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,LOTS_OF_MONEY,MAILING_LIST_MULTI,MONEY_NOHTML, 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 A5805C07E99 for ; Fri, 9 Jul 2021 08:50:27 +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 68FB8611AB for ; Fri, 9 Jul 2021 08:50:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 68FB8611AB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc: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=8TL6DajyCVwJg7rM+MQwzq95ddCZqUFKgRxQFrukC3Y=; b=aPWWAsyr4iE9nW C/aeRUOrSGi4XXy6J3nKB0YRzyGmkXDzedcDPt0nVafD8X6OWS8Qfml6hF0WVNzIoL4/D8sqm0PYy +95bmxxSTo/buJFUtHvYw325DcQqZhXBpuGTl8ODP28/KXkR15oLht4w/93yiP7UU3beeIe8IFQbW pOjNwRojDznbyZQ8SDj7POBsBQc13m5ZN233mvI5x84y0uBQJWEIlNQ9uYcV5w9mBM2AmNQQDswmZ dQ+dyNe4tczQvy39GfWtX3ZPeGXzIKcHWSVqyaZsXROFfdAGNbAprQDC9dQ0EgHk1uRZPNKZTQLHu XvbGnsZVfFT7PHtdi+Hw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m1mBo-001CZg-Mc; Fri, 09 Jul 2021 08:48:52 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1m1mBk-001CZC-Rr for linux-arm-kernel@lists.infradead.org; Fri, 09 Jul 2021 08:48:50 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6F25A611AB; Fri, 9 Jul 2021 08:48:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625820528; bh=pQ92xSOMcEDltChjsdB6HAKdM9sWgzL0fKaeJ/tnu8E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ORctpzD/biOqGGpC6RyP8BsFLsDj69jUkH7hiaqXUMBjQwBjgSvTy3Cid5PHV8OS8 zMrBrL4pxDnyjj/J7mjw4sb5Amb6FH46bTFySzlRSFru3FVtoAdu0ev3LR72bktVKc ikH7ps/mQqhXOS09EFt4gxG5BgsxBzBNdTeWqOkui/GwDa2Lter7EJz1U0UxKwXB85 X+COt/JcDHP9zSuIdkMqI7Gv9tbZT5qEtUDGDEoYjv9K1CrY6qR6ezcAJusBW3U9GJ kkpWlqgaPXkHfMl6/w/LVN5YmjiPyKRXlCn8Zr9hJtFfjN3Yd9oEvXgfGuJVWXvEto g6lJDMOWzZIMg== Date: Fri, 9 Jul 2021 09:48:42 +0100 From: Will Deacon To: Jeffrey Hugo Cc: Arnd Bergmann , Yassine Oudjana , Marc Zyngier , Robin Murphy , Catalin Marinas , Ard Biesheuvel , Android Kernel Team , Linux ARM , Mark Rutland , Vincent Whitchurch , linux-arm-msm , Bjorn Andersson Subject: Re: [PATCH] arm64: cache: Lower ARCH_DMA_MINALIGN to 64 (L1_CACHE_BYTES) Message-ID: <20210709084842.GA24432@willie-the-truck> References: <87zguz7b6b.wl-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210709_014848_975886_4290A691 X-CRM114-Status: GOOD ( 23.55 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jul 08, 2021 at 02:59:28PM -0600, Jeffrey Hugo wrote: > On Wed, Jul 7, 2021 at 8:41 AM Jeffrey Hugo wrote: > > > > On Wed, Jul 7, 2021 at 3:30 AM Arnd Bergmann wrote: > > > > > > On Tue, Jul 6, 2021 at 6:20 PM Will Deacon wrote: > > > > > > > > I think the million dollar question is whether the 128-byte cache-lines > > > > live in a cache above the PoC or not. If it's just a system level cache > > > > through which all DMA is "coherent", then it doesn't matter. > > > > > > On Wed, Jul 7, 2021 at 10:24 AM Yassine Oudjana > > > wrote: > > > > > > > > On Wednesday, July 7th, 2021 at 12:33 AM, Arnd Bergmann wrote: > > > > > On Tue, Jul 6, 2021 at 7:15 PM Yassine Oudjana y.oudjana@protonmail.com wrote: > > > > > > > > > > > > $ numactl -C 0 line -M 1M > > > > > > 128 > > > > > > $ numactl -C 3 line -M 1M > > > > > > 128 > > > > > > > > > > Can you rerun the the 'line' test with '-M 128K' to see if that confirms the 64 > > > > > byte L1 line size that the 'cache' test reported? > > > > > > > > $ numactl -C 0 line -M 128K > > > > 64 > > > > $ numactl -C 3 line -M 128K > > > > 64 > > > > > > Ok, so this seems to confirm that the L1 uses 64 byte lines, while the L2 (or > > > possibly L3) uses 128 byte lines. > > > > > > On Wed, Jul 7, 2021 at 12:27 AM Bjorn Andersson > > > wrote: > > > > > > > > I can confirm that MSM8996, and a few derivatives, has 128 byte cache lines. > > > > > > Ok, thanks. Assuming this is an outer cache and the L1 indeed has a smaller line > > > size, can you also confirm that this 128 byte lines are north of the point of > > > coherency? > > > > Finding this old documentation has been painful :) > > > > L0 I 64 byte cacheline > > L1 I 64 > > L1 D 64 > > L2 unified 128 (shared between the CPUs of a duplex) > > > > I believe L2 is within the POC, but I'm trying to dig up the old > > documentation to confirm. > > Was able to track down a friendly hardware designer. The POC lies > between L2 and L3. Hope this helps. Damn, yes, it's bad news but thanks for chasing it up. I'll revert the patch at -rc1 and add a comment about MSM8996. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel