From owner-svn-src-all@freebsd.org Wed Dec 14 19:49:06 2016 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9A884C807AD; Wed, 14 Dec 2016 19:49:06 +0000 (UTC) (envelope-from mavbsd@gmail.com) Received: from mail-wm0-x241.google.com (mail-wm0-x241.google.com [IPv6:2a00:1450:400c:c09::241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 41D0C13D1; Wed, 14 Dec 2016 19:49:06 +0000 (UTC) (envelope-from mavbsd@gmail.com) Received: by mail-wm0-x241.google.com with SMTP id g23so1382505wme.1; Wed, 14 Dec 2016 11:49:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:subject:to:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding; bh=FCMpIC4poDpsidj3S82JRBpKjT9Gq/XUZ65tYyrMIZ8=; b=uriIXybuvKl8RZ7BYK+alRIVVnjv/AuHuhrUBivNc9VsFW3rRK/xjPWrCZT2ALXrz9 ag86CKPxOqifmVV+aGwIIq6p7bZK8nq3BmteoUrn6pnrlFMJKLOISQHOEdaiGajC0efu 9F0rHQ+UOtgWTKgIhNrPacYitZAnU/1vI4PH6az2PcJpAxFf7mZTQ+H2cR0m8U3t4aqM 9/e8noEt65o5QtWFQWxg+JOME6Zrb9Wu7NkoVDVWtzlPCBQepVw2/jqi96whyZt2iWGW jGjl0m3HApO0+t402z74AAZNlCal3FfLtpB66Re8XIQaJpQHe1vaFDYGHqYUAPZhSFYC W1Uw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:subject:to:references:from:message-id :date:user-agent:mime-version:in-reply-to:content-transfer-encoding; bh=FCMpIC4poDpsidj3S82JRBpKjT9Gq/XUZ65tYyrMIZ8=; b=llSdfXGewq/0EkvQwG5ulC3HlAtc6PgQEFY3tHn+AkErtbyySfbiUlM+OuymfkBKyr m53SdhqJfdOHYSN4DbtzpN9e9rGpnv4ILrH/wYGgMuE6rt8ZQ2CsTE4ImOgwf2GlJaOe co5ps5LxDnMnVrGOX1dEqKcxn9lo4QMzFJ7zdsgWx8qFQvbI/tzyRPNsAIUch0b0+TEW jhicsqD8uEXNtTzBGl6PNpRuW2hqLxZoLE4XfHmS06VpjWJ94AA1UzadeTEr2C2L1qsR fdrFzabhTZwHKtCG1h40PGiA8k3uC1Bwhl5UJbZYBi3h3xlOA5ebHg0JWznnYVzr1gLA CHUw== X-Gm-Message-State: AKaTC02gJC2SSk2heJ56hl2MZxEip59W/1hn4GcoW6vNkz5d8P2DF4FuGNpcQuF20sMZUw== X-Received: by 10.25.125.132 with SMTP id y126mr35014934lfc.86.1481744943226; Wed, 14 Dec 2016 11:49:03 -0800 (PST) Received: from spectre.mavhome.dp.ua ([134.249.139.101]) by smtp.gmail.com with ESMTPSA id c78sm10975384lfc.39.2016.12.14.11.49.02 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 14 Dec 2016 11:49:02 -0800 (PST) Sender: Alexander Motin Subject: Re: svn commit: r309714 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs To: Andriy Gapon , src-committers@FreeBSD.org, svn-src-all@FreeBSD.org, svn-src-head@FreeBSD.org References: <201612081558.uB8Fw4xA027508@repo.freebsd.org> From: Alexander Motin Message-ID: Date: Wed, 14 Dec 2016 21:49:01 +0200 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 14 Dec 2016 19:49:06 -0000 On 14.12.2016 14:03, Andriy Gapon wrote: > On 08/12/2016 17:58, Alexander Motin wrote: >> This change switches zio_timestamp_compare() from comparing uninitialized >> io_offset to really populated io_bookmark values. I haven't decided yet >> what to do with timestampts, but on simple tests this change gives the >> same peformance results by just making code to work as declared. > > I think that we should just enable precise timestamps. > I just can't see them noticeably hurting performance given the amount of > calculations, memory allocations, locking, etc, that ZFS already has. > And there are layers above and below ZFS too. It is orthogonal to this change and can be done any time, if decided. I worried mostly about some older systems still using HPET or ACPI timecounters, where half dozen extra timer calls per single I/O may be quite expensive. I've recently reviewed all places where ZFS calls gethrtime(), and found that in most of them precision is not needed, even 1 second would be enough, not even 1/hz. I've found only two cases where precision is important, both about ZIO sorting in different places (this is one of the two), and both of them are now workarounded now by using offset as secondary key. -- Alexander Motin