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 5F564C6379F for ; Tue, 17 Jan 2023 16:59:32 +0000 (UTC) Received: from picard.linux.it (localhost [IPv6:::1]) by picard.linux.it (Postfix) with ESMTP id 1BE213CD9EF for ; Tue, 17 Jan 2023 17:59:29 +0100 (CET) Received: from in-2.smtp.seeweb.it (in-2.smtp.seeweb.it [217.194.8.2]) (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 E85C63C7197 for ; Tue, 17 Jan 2023 17:59:19 +0100 (CET) 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 52660600819 for ; Tue, 17 Jan 2023 17:59:19 +0100 (CET) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 3EA5621F69; Tue, 17 Jan 2023 16:59:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1673974758; 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=rp/tbTZJPO1j85edWsIAoiFfak+DCsEQczf4zAWvpzw=; b=lyaB5Ds5uNbF7ypCvVvDbZCg2cO7KDGO6xhI8q7MTBH2h9duYt9wmmPJ/g3/rtVCMrCxw1 ZVkXZzCfzPb9xH3Xv2luJ65LMeXkmA67aR82pgWr+G4e5H5gFs5S51BB+reMBsLHRRXNdS yDnae5/x1084fHqqjafXqJ7lqPvtDLo= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1673974758; 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=rp/tbTZJPO1j85edWsIAoiFfak+DCsEQczf4zAWvpzw=; b=eBpP8ddfE6bOd2muza8z4c3M5D/x2QcJOJbrpdiox+WW0+pdPBi4Y2tsZgRzz25HqUlCjj 0RJKgdwgr98n0vCw== 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 0BC3E2C141; Tue, 17 Jan 2023 16:59:18 +0000 (UTC) References: <20230116074101.1264-1-wegao@suse.com> <87fscawlku.fsf@suse.de> <20230117021631.GA20825@aa> <877cxlwk66.fsf@suse.de> User-agent: mu4e 1.8.13; emacs 28.2 From: Richard Palethorpe To: Cyril Hrubis Date: Tue, 17 Jan 2023 16:50:49 +0000 Organization: Linux Private Site In-reply-to: Message-ID: <87tu0pumfu.fsf@suse.de> MIME-Version: 1.0 X-Virus-Scanned: clamav-milter 0.102.4 at in-2.smtp.seeweb.it X-Virus-Status: Clean Subject: Re: [LTP] [PATCH v1] readahead02.c: Use fsync instead of sync 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, Cyril Hrubis writes: > Hi! >> > The motivation of this change is base on the https://github.com/linux-test-project/ltp/issues/972 >> > which give following suggestion: >> > "As we run the test inside a loop device I guess that we can also >> > sync and drop caches just for the device, which should be faster >> > than syncing and dropping the whole system. Possibly we just need >> > to umount it and mount it again." >> >> I see. Well unless Cyril can show that the test is actually failing >> somewhere (or there is a strong logical argument this will cause a >> failure). Then this task is still valid, but low priority IMO. > > We do sync more than needed here, since we are looking at the per device > counters we have to sync just the device we mount for the test, so this > is optimization for the case that the system has many dirty cases and > will need seconds or a minute to write them to the pernament storage. > >> > But currently i can not find any API to sync and drop caches just >> > ONLY for device, so base my view just replace sync whole >> > system to single file also can make a small help. >> >> If we don't have one or more concrete failures to focus on then we >> really have to research whether fsync (or syncfs FYI) or unmounting the >> device are the correct thing to do. They will all have subtly different >> effects. > > Looking at the code closely I'm starting to think that the sync is not > required at all. What we do in the test is that we create file and sync > it to the external storage. Then we read it a few times and mesure > differences in cache. As far as I can tell we just need to drop the page > cache after we have read the file. What do you think? > > In any case I would avoid changing the test before the release, but it's > certainly something we can look at after that. I still think same as before. It may be valid to drop sync or whatever, but it's just not important compared to actively failing tests. -- Thank you, Richard. -- Mailing list info: https://lists.linux.it/listinfo/ltp