From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Thu, 12 Mar 2026 15:44:59 +0100 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1w0hHW-00ArNy-3D for lore@lore.pengutronix.de; Thu, 12 Mar 2026 15:44:59 +0100 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1w0hHX-0004Op-4P for lore@pengutronix.de; Thu, 12 Mar 2026 15:44:59 +0100 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:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=hSu+fSSoR7hbzINhlXex3YnZxUehf13HkRgJ+KYWghE=; b=aKcRYe0C3hmByoDGnR/nr7vgaj JbNulPjKJsoQqRjhL2U7J9kJp1qm1+DXd/BD50W27BG2tqqz82sulDW2j7eYVsv4HvvJpWD+BbRDk KF4xOOejjFMod/t515J2fY2RyF+gO2rAh4fNgAVaqV7LhF/CW3L4NsmDhUo/a9o916xUAA/pOLUvG bW5M2lxYA0cXGsj47p5c4/gZ5zj5FgacUEyKaggCr2QPklNe+LwQO7tpzEAG90DcL6sPI31Zh5W7g Kv4JE0vpep77J244hdKDfklezwWbKsGXldqUt66ImhJ3fnnjS54roFVRwMs0LVqg6Bh2IUn2+6w0B T/BsoZEw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w0hH8-0000000EEUk-1t45; Thu, 12 Mar 2026 14:44:34 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1w0hH4-0000000EESB-3aza for barebox@lists.infradead.org; Thu, 12 Mar 2026 14:44:33 +0000 Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1w0hH3-00048O-6L; Thu, 12 Mar 2026 15:44:29 +0100 Received: from dude05.red.stw.pengutronix.de ([2a0a:edc0:0:1101:1d::54]) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1w0hH1-0052Nc-26; Thu, 12 Mar 2026 15:44:29 +0100 Received: from [::1] (helo=dude05.red.stw.pengutronix.de) by dude05.red.stw.pengutronix.de with esmtp (Exim 4.98.2) (envelope-from ) id 1w0hH2-000000093bb-3o8T; Thu, 12 Mar 2026 15:44:28 +0100 From: Ahmad Fatoum To: barebox@lists.infradead.org Cc: Ahmad Fatoum Date: Thu, 12 Mar 2026 15:44:22 +0100 Message-ID: <20260312144428.2158727-2-a.fatoum@pengutronix.de> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260312144428.2158727-1-a.fatoum@pengutronix.de> References: <20260312144428.2158727-1-a.fatoum@pengutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260312_074431_000796_1A225824 X-CRM114-Status: GOOD ( 10.37 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-3.8 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.2 Subject: [PATCH 2/5] tftp: warn when seek-heavy access wastes network bandwidth X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) Patterns that work ok-ish on local file systems like opening a file repeatedly and/or seeking to different offsets can have catastrophic performance on TFTP, because every seek must read and discard data up to the desired offset. Add a lightweight heuristic accumulating the total bytes discarded by seeks and emit a one-time warning, once we exceed 4 MiB of wasted reads. Signed-off-by: Ahmad Fatoum --- fs/tftp.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/tftp.c b/fs/tftp.c index dd4804041cde..e5a276ed5cae 100644 --- a/fs/tftp.c +++ b/fs/tftp.c @@ -902,6 +902,7 @@ static int tftp_read(struct file *f, void *buf, size_t insize) static int tftp_lseek(struct file *f, loff_t pos) { + static loff_t seek_discard_total; int ret = 0; char *buf; loff_t f_pos = f->f_pos; @@ -931,6 +932,13 @@ static int tftp_lseek(struct file *f, loff_t pos) out_free: free(buf); + + seek_discard_total += f_pos - f->f_pos; + if (seek_discard_total > SZ_4M) + pr_warn_once("excessive seeking (%lld bytes discarded so far);" + " consider copying file to RAM first?\n", + seek_discard_total); + if (ret < 0) { /* * Update f->pos even if the overall request -- 2.47.3