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 4DCC2C4708E for ; Tue, 6 Dec 2022 15:32:06 +0000 (UTC) Received: from picard.linux.it (localhost [IPv6:::1]) by picard.linux.it (Postfix) with ESMTP id 6E3CE3CC1DF for ; Tue, 6 Dec 2022 16:32:02 +0100 (CET) Received: from in-4.smtp.seeweb.it (in-4.smtp.seeweb.it [217.194.8.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-384)) (No client certificate requested) by picard.linux.it (Postfix) with ESMTPS id D52723C2B4D for ; Tue, 6 Dec 2022 16:31:49 +0100 (CET) Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) (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-4.smtp.seeweb.it (Postfix) with ESMTPS id 2010A10000C6 for ; Tue, 6 Dec 2022 16:31:48 +0100 (CET) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 17E6821C31 for ; Tue, 6 Dec 2022 15:31:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1670340708; 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=udQ8JHwjV3l1wpYvxEUEbUBg9fzr6r7zahbE4PyH428=; b=QOKEzVQ1hkIKhUAcAcGRp6SthgRpKQHAGkE9N8CmR/BevNbSRo+tEQoVUzrXYgihtNNVsq MtYcM2+auUw9nAcbjdXBMcHackdbAUNzXFX2I6WPR8oZQngwIiNHMdka43M40cXE0DkTbp k2WFQFxGCVifvZsY47a5sszFUe9Yi5Q= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1670340708; 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=udQ8JHwjV3l1wpYvxEUEbUBg9fzr6r7zahbE4PyH428=; b=99/TEO8rJnuqtLpOPW7oGcuBft3tEmlkI+Fk6DBtkko4EN4gUQQpLxYyGe0RJs5wyM6J3W EA83ftFTZSc2EsAg== 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 E45B32C142; Tue, 6 Dec 2022 15:31:47 +0000 (UTC) References: <20221206115329.17760-1-rpalethorpe@suse.com> <20221206115329.17760-2-rpalethorpe@suse.com> User-agent: mu4e 1.8.11; emacs 28.2 From: Richard Palethorpe To: Cyril Hrubis Date: Tue, 06 Dec 2022 15:22:27 +0000 Organization: Linux Private Site In-reply-to: Message-ID: <87edtctuos.fsf@suse.de> MIME-Version: 1.0 X-Virus-Scanned: clamav-milter 0.102.4 at in-4.smtp.seeweb.it X-Virus-Status: Clean Subject: Re: [LTP] [PATCH 2/2] fill_fs: Ensure written data is not easily compressed 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! >> --- a/lib/tst_fill_fs.c >> +++ b/lib/tst_fill_fs.c >> @@ -16,13 +16,20 @@ void tst_fill_fs(const char *path, int verbose) >> { >> int i = 0; >> char file[PATH_MAX]; >> - char buf[4096]; >> + static char buf[4096]; > > I'm not sure if caching the random data is worth here, I bet that > reading the random data would be neglectible to the rest of the write > operations we do. I suppose that instead of writing random lengths we could just copy /dev/urandom to in static chunks of a reasonable size. Furthermore we can use copy_file_range on newer kernels. -- Thank you, Richard. -- Mailing list info: https://lists.linux.it/listinfo/ltp