From nobody Sat Oct 09 19:41:28 2021 X-Original-To: freebsd-hackers@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 0D36D17E0242 for ; Sat, 9 Oct 2021 19:41:37 +0000 (UTC) (envelope-from sebastian.huber@embedded-brains.de) Received: from dedi548.your-server.de (dedi548.your-server.de [85.10.215.148]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4HRb682PRzz4VCX for ; Sat, 9 Oct 2021 19:41:36 +0000 (UTC) (envelope-from sebastian.huber@embedded-brains.de) Received: from sslproxy03.your-server.de ([88.198.220.132]) by dedi548.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92.3) (envelope-from ) id 1mZIDp-000GaE-DZ for freebsd-hackers@freebsd.org; Sat, 09 Oct 2021 21:41:29 +0200 Received: from [82.100.198.138] (helo=mail.embedded-brains.de) by sslproxy03.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mZIDp-000UZA-Ab for freebsd-hackers@freebsd.org; Sat, 09 Oct 2021 21:41:29 +0200 Received: from localhost (localhost [127.0.0.1]) by mail.embedded-brains.de (Postfix) with ESMTP id 10F3E480082 for ; Sat, 9 Oct 2021 21:41:29 +0200 (CEST) Received: from mail.embedded-brains.de ([127.0.0.1]) by localhost (zimbra.eb.localhost [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id j38dUGB4ncGX for ; Sat, 9 Oct 2021 21:41:28 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by mail.embedded-brains.de (Postfix) with ESMTP id B708A480107 for ; Sat, 9 Oct 2021 21:41:28 +0200 (CEST) X-Virus-Scanned: amavisd-new at zimbra.eb.localhost Received: from mail.embedded-brains.de ([127.0.0.1]) by localhost (zimbra.eb.localhost [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id xYbz3OB8hmuc for ; Sat, 9 Oct 2021 21:41:28 +0200 (CEST) Received: from [10.10.171.10] (unknown [10.10.171.10]) by mail.embedded-brains.de (Postfix) with ESMTPSA id 96EF2480082 for ; Sat, 9 Oct 2021 21:41:28 +0200 (CEST) To: freebsd-hackers@freebsd.org From: Sebastian Huber Subject: Why was the timehands_count sysctl added? Message-ID: <2d1d2a6d-ec6b-7f52-8af3-09a833c52820@embedded-brains.de> Date: Sat, 9 Oct 2021 21:41:28 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 List-Id: Technical discussions relating to FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-hackers List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-hackers@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Authenticated-Sender: smtp-embedded@poldinet.de X-Virus-Scanned: Clear (ClamAV 0.103.3/26317/Sat Oct 9 10:19:24 2021) X-Rspamd-Queue-Id: 4HRb682PRzz4VCX X-Spamd-Bar: / Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=pass (mx1.freebsd.org: domain of sebastian.huber@embedded-brains.de designates 85.10.215.148 as permitted sender) smtp.mailfrom=sebastian.huber@embedded-brains.de X-Spamd-Result: default: False [-0.21 / 15.00]; SUBJECT_ENDS_QUESTION(1.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; R_SPF_ALLOW(-0.20)[+ip4:85.10.215.148]; MIME_GOOD(-0.10)[text/plain]; TO_DN_NONE(0.00)[]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; RCPT_COUNT_ONE(0.00)[1]; NEURAL_HAM_MEDIUM(-0.98)[-0.985]; RCVD_TLS_LAST(0.00)[]; NEURAL_HAM_SHORT(-0.86)[-0.859]; NEURAL_SPAM_LONG(0.93)[0.930]; DMARC_NA(0.00)[embedded-brains.de]; ARC_NA(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:24940, ipnet:85.10.192.0/18, country:DE]; RCVD_COUNT_SEVEN(0.00)[8]; HAS_X_AS(0.00)[] X-ThisMailContainsUnwantedMimeParts: N Hello, I synchronize currently the port of the FreeBSD timecounters to RTEMS=20 and came across a change in 2019 which I do not understand. Some time=20 ago the timehands were reduced from 10 to two: https://reviews.freebsd.org/D7302 In 2019 this changed again to be up to 16: https://reviews.freebsd.org/D21563 The corresponding sysctl is not documented: https://www.freebsd.org/cgi/man.cgi?query=3Dtimecounters&sektion=3D4 Does someone know why this sysctl to select the count of timehands was=20 added? Is this a performance optimization for some systems? Best regards, Sebastian --=20 embedded brains GmbH Herr Sebastian HUBER Dornierstr. 4 82178 Puchheim Germany email: sebastian.huber@embedded-brains.de phone: +49-89-18 94 741 - 16 fax: +49-89-18 94 741 - 08 Registergericht: Amtsgericht M=C3=BCnchen Registernummer: HRB 157899 Vertretungsberechtigte Gesch=C3=A4ftsf=C3=BChrer: Peter Rasmussen, Thomas= D=C3=B6rfler Unsere Datenschutzerkl=C3=A4rung finden Sie hier: https://embedded-brains.de/datenschutzerklaerung/