From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Wed, 02 Nov 2022 09:51:54 +0100 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1oq9TW-00C4ED-DX for lore@lore.pengutronix.de; Wed, 02 Nov 2022 09:51:54 +0100 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oq9TU-0007W8-Ub for lore@pengutronix.de; Wed, 02 Nov 2022 09:51:53 +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: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:In-Reply-To:References:List-Owner; bh=GSzo9rXaelsBDa6IywQ0g6H3XUvMIVIFKEhbgrfVq0g=; b=m+VuBT9Pts0ylCS1UnG9Kq+OJc rwCpDEW0SluI5iR9uM6l9J22d51+ygseiVB/9fLSvBNVCfDZW173mCP4t+4g1WskSzRnrrrJ0Cm2+ 9yaOIl5BB/A475tar3fmOA/NCe8FscMYPEUgmRA7c2KMtFHODhr+Yh0M47B2jz4oEfO6lVgJRYIr7 MtCe6WFhApXCRevnj8gzzswj3aRawDBBHF7fTe26Gg7srT69nUZKRc1RAV7Q0BAYbXx1FJ8OC8Xrz a3MVoM2v8xsmIHp6mB7c1LD2lFoVsI8ppKvanOeb0nz+ro3WFJ6LqvIt4FuALoWGKm/1rXPhiAMGK kxBEnFlg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oq9S8-009D2T-80; Wed, 02 Nov 2022 08:50:28 +0000 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oq9S4-009CzX-9H for barebox@lists.infradead.org; Wed, 02 Nov 2022 08:50:25 +0000 Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oq9S0-00070r-Mc; Wed, 02 Nov 2022 09:50:20 +0100 Received: from [2a0a:edc0:0:1101:1d::ac] (helo=dude04.red.stw.pengutronix.de) by drehscheibe.grey.stw.pengutronix.de with esmtp (Exim 4.94.2) (envelope-from ) id 1oq9S0-001puL-VO; Wed, 02 Nov 2022 09:50:20 +0100 Received: from afa by dude04.red.stw.pengutronix.de with local (Exim 4.94.2) (envelope-from ) id 1oq9Rz-00896f-Ga; Wed, 02 Nov 2022 09:50:19 +0100 From: Ahmad Fatoum To: barebox@lists.infradead.org Cc: Ahmad Fatoum Date: Wed, 2 Nov 2022 09:50:17 +0100 Message-Id: <20221102085017.1941580-1-a.fatoum@pengutronix.de> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221102_015024_363205_E0167329 X-CRM114-Status: GOOD ( 10.04 ) 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.ext.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-5.2 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: [PATCH] commands: uptime: add note about caveats X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.ext.pengutronix.de) Normally timer overrun is not that much of a problem, because there where it matters, we usually have an is_timeout() in the loop that reads the timer often enough. This doesn't necessarily hold for the new uptime command and basically anything can happen between subsequent calls and if get_time_ns() is not called often enough during that time, we end up with an inaccurate uptime. Mention this in the extended help text. Signed-off-by: Ahmad Fatoum --- Can be squashed into original commit. --- commands/uptime.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/commands/uptime.c b/commands/uptime.c index a9a8c650b698..d67538631c8f 100644 --- a/commands/uptime.c +++ b/commands/uptime.c @@ -66,6 +66,9 @@ static int do_uptime(int argc, char *argv[]) BAREBOX_CMD_HELP_START(uptime) BAREBOX_CMD_HELP_TEXT("This command formats the number of elapsed nanoseconds") BAREBOX_CMD_HELP_TEXT("as measured with the current clocksource") +BAREBOX_CMD_HELP_TEXT("Note: Timekeeping is co-operative. If long running code does") +BAREBOX_CMD_HELP_TEXT("not use delay/is_timeout/get_time_ns/getchar functions") +BAREBOX_CMD_HELP_TEXT("timer may overrun resulting in incorrect results") BAREBOX_CMD_HELP_TEXT("Options:") BAREBOX_CMD_HELP_OPT ("-n", "output elapsed time in nanoseconds") BAREBOX_CMD_HELP_END -- 2.30.2