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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id C81CDCC6B27 for ; Wed, 14 Oct 2026 09:03:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type: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=s7km/o15RrE3t/oF+oZWM5/Ow0NTPkXAPHXcErgX/7Q=; b=F331rvk5alOqC+yRuKU6L4lTrP 01g4ZXNj6avflm+eB6wF1mCXcqtZF0rC34Qc3hWLMR46mk71SLwbBP8nK6531563xSlgCmjI/z1Kw MRo9EaOF7FDIQNFWWer0E7GC88FB9VGRgiQ8GMrbAI7XJh86TcXw3X5VRDS0EXvKSOXmUVAHHrxz/ NLQGmmjF+xDIqlCyUr6u3vPlPEykxZq8FVY+ppnD/wlvsOP/J848BRBnwJxMSxFpOHoS3atwv51dj 5cdB0VdJzETlM78h7vJYpuWHuFR6mXu5X3LOqNkdSFThfSd6n9KqrHR1zMxzeFLhagXTwIsyt5H92 K65ellDA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xGutC-0000000EyIf-2BrT; Wed, 14 Oct 2026 09:03:10 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xGutA-0000000EyI5-3EpQ for linux-arm-kernel@lists.infradead.org; Wed, 14 Oct 2026 09:03:09 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A34661596; Wed, 14 Oct 2026 02:03:04 -0700 (PDT) Received: from arm.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 334523F7B4; Wed, 14 Oct 2026 02:03:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1791968587; bh=7A05GsuFKMCSCusEHwAE+GYyrPrUSYy7spZfdDk0d+k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YoKyykGBv0d5ue1IA9pDqAIBz0IsC4ds1IPAVcDI3VyYRFIpLsbgh+PjOfqESJYLM nKkMwtRvL8O0B3NL+W7trm/B/1/A1l/+YsTkw6Y3cm3AJ6d5wvTe7xoa967irdGd/t ou+P9TNgOMpuhAmmkHefuL9+QewRyRRDClluU2po= Date: Wed, 14 Oct 2026 10:03:02 +0100 From: Catalin Marinas To: Linus Walleij Cc: Muhammad Usama Anjum , Leonardo Bras , Will Deacon , Marc Zyngier , Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev Subject: Re: [PATCH v2] arm64: clear_page[s] using memset Message-ID: References: <20260916-aarch64-clear-pages-c-v2-1-0393769f7912@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261014_020308_858697_9A918684 X-CRM114-Status: GOOD ( 19.12 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Oct 13, 2026 at 06:28:54PM +0200, Linus Walleij wrote: > On Tue, Oct 13, 2026 at 3:04 PM Catalin Marinas wrote: > > > Trying to make sense of the above. So based on -next of 22nd of > > September, the table means: > > > > vanilla - next/master on that day (current clear_page()) > > patch - memset()-based clear_page() patch (Linus's patch) > > stnp - vanilla clear_page() without DC ZVA > > patch_stp - memset()-based clear_page() patch without DC ZVA > > > > I assume the vanilla vs patch columns are just noise. Well, there's a > > -1.17% regression (not flagged) on Ampere but what's the standard > > deviation for this column? Similarly for the -1.15% on the AWS patch_stp > > test (vs stnp in the same test, it's no worse). > > > > Vanilla vs stnp shows a regression on Ampere, however that's expected as > > we no longer do the DC ZVA. Interestingly, the patch_stp result doesn't have > > this regression, so I reckon DC ZVA behaves mostly in line with STP on > > this hardware. > > > > Basically I was looking for the stnp vs patch_stp results. If I read it > > correctly, there's no significant change going from non-temporal to > > temporal stores (and a small improvement for Ampere). Assuming future > > FEAT_MOPS will have similar behaviour, moving clear_page() to memset() > > shouldn't cause any regressions. Before FEAT_MOPS, we'll use DC ZVA here > > anyway. > > That almost sounds like an Acked-by if Usama can confirm your > assumptions above! It's queued but we can revert it if it shows real regression. -- Catalin