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 picard.linux.it (picard.linux.it [213.254.12.146]) (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 92979C83F14 for ; Wed, 30 Aug 2023 08:30:22 +0000 (UTC) Received: from picard.linux.it (localhost [IPv6:::1]) by picard.linux.it (Postfix) with ESMTP id ACE843CC0FF for ; Wed, 30 Aug 2023 10:30:20 +0200 (CEST) Received: from in-2.smtp.seeweb.it (in-2.smtp.seeweb.it [IPv6:2001:4b78:1:20::2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-384) server-digest SHA384) (No client certificate requested) by picard.linux.it (Postfix) with ESMTPS id 289DB3C527F for ; Wed, 30 Aug 2023 10:30:08 +0200 (CEST) Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by in-2.smtp.seeweb.it (Postfix) with ESMTPS id 84F9460257B for ; Wed, 30 Aug 2023 10:30:07 +0200 (CEST) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id D06A621854; Wed, 30 Aug 2023 08:30:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1693384206; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=aRucCyRQxwkBAao4kcuH7sY/HVMRF5IVg1/tZU0r6Jg=; b=Cc9bDzEzTrm+6kReLccdRX0MdSNDIuiaZXg3LF6Njx1r49bQqvm1ylOwSf67zjA//4RBnO /BWNiH7GmgPTpym4yp0mlABb60FRrQB7q1uZ6TnFkeRNANRrBVISeb0/m1HDCL7ScDtrns uFtwr9yipmJiYZcsqGQ0sQIdwUbQVsU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1693384206; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=aRucCyRQxwkBAao4kcuH7sY/HVMRF5IVg1/tZU0r6Jg=; b=QX2g9zINxGGSPaKMZ/kQ741dnE6I7pOc48u5uz1097vU1pq9IXOPk5HVJKdw/qG9UIlSmm Dk0VDgr8w1jAQBCQ== Received: from g78 (unknown [10.163.28.198]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 0ADA52C142; Wed, 30 Aug 2023 08:30:05 +0000 (UTC) References: <20230803015149.69906-1-iwienand@redhat.com> <20230808035641.364676-2-iwienand@redhat.com> User-agent: mu4e 1.10.6; emacs 29.1 From: Richard Palethorpe To: Ian Wienand Date: Wed, 30 Aug 2023 09:20:44 +0100 Organization: Linux Private Site In-reply-to: <20230808035641.364676-2-iwienand@redhat.com> Message-ID: <87il8xhr05.fsf@suse.de> MIME-Version: 1.0 X-Virus-Scanned: clamav-milter 1.0.1 at in-2.smtp.seeweb.it X-Virus-Status: Clean Subject: Re: [LTP] [PATCH v2] kernel/device-drivers/zram/zram01.sh : don't fill from /dev/zero X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: rpalethorpe@suse.de Cc: ltp@lists.linux.it Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ltp-bounces+ltp=archiver.kernel.org@lists.linux.it Sender: "ltp" Hello, Ian Wienand writes: > I have a system (virtualized aarch64, 4.18.0 kernel) that is > consistently failing the zram01.sh test as it tries to divide the > memory stats by zero. This has been reported before at [1] without > resolution. > > After some investigation [2] my conclusion is that this zero value > represents the pages allocated for compressed storage in the zram > device, and due to same-page deduplication the extant method of > filling with all-zeros can indeed lead us to not having any compressed > data to measure. > > This is visible in the occasional divide-by-zero error, but in the > bigger picture means this test is not exercising the compression path > as desired. Do zram{02,03} already do something similar? In any case I'd prefer to see a zram04 written in C if some coverage is missing. -- Thank you, Richard. -- Mailing list info: https://lists.linux.it/listinfo/ltp