From owner-freebsd-arch@freebsd.org Sat Aug 26 18:46:55 2017 Return-Path: Delivered-To: freebsd-arch@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 82EA4DD87D5 for ; Sat, 26 Aug 2017 18:46:55 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 1A4F175AD5; Sat, 26 Aug 2017 18:46:54 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.15.2/8.15.2) with ESMTPS id v7QIkoiL073907 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Sat, 26 Aug 2017 21:46:50 +0300 (EEST) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua v7QIkoiL073907 Received: (from kostik@localhost) by tom.home (8.15.2/8.15.2/Submit) id v7QIkogv073906; Sat, 26 Aug 2017 21:46:50 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Sat, 26 Aug 2017 21:46:50 +0300 From: Konstantin Belousov To: Don Lewis Cc: freebsd-rwg@pdx.rh.CN85.dnsmgr.net, avg@freebsd.org, freebsd-arch@freebsd.org Subject: Re: ULE steal_idle questions Message-ID: <20170826184650.GS1700@kib.kiev.ua> References: <201708261812.v7QIC2eJ074443@pdx.rh.CN85.dnsmgr.net> <201708261829.v7QITTYw053896@gw.catspoiler.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201708261829.v7QITTYw053896@gw.catspoiler.org> User-Agent: Mutt/1.8.3 (2017-05-23) X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on tom.home X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 26 Aug 2017 18:46:55 -0000 On Sat, Aug 26, 2017 at 11:29:29AM -0700, Don Lewis wrote: > I actually haven't noticed that problem on my package build boxes. I've > experienced decent interactive performance even when the load average is > in the 60 to 80 range. I also have poudriere configured to use tmpfs > and the only issue I run into is when it starts getting heavily into > swap (like 20G) and I leave my session idle for a while, which lets my > shell and sshd get swapped out. Then it takes them a while to wake up > again. Once they are paged in, then things feel snappy again. This is > remote access, so I can't comment on what X11 feels like. I believe what people complain about is the following scenario: they have some interactive long living process, say firefox or mplayer. The process' threads consume CPU cycles, so the ULE interactivity detection logic actually classifies the threads as non-interactive. This is not much problematic until a parallel build starts where toolchain processes are typically short-lived. This makes them classified as interactive, and their dynamic priority are lower than the priority of long-lived threads which are interactive by user perception. I did not analyzed the KTR dumps but this explanation more or less coincides with the system slugginess when attempt to use mplayer while heavily oversubscribed build (e.g. make -j 10 on 4 cores x 2 SMT machine) is started.