From nobody Thu Mar 23 20:54:07 2023 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 4PjHdN0Ngkz40JrH for ; Thu, 23 Mar 2023 20:54:16 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (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 4PjHdM5j3Dz4765; Thu, 23 Mar 2023 20:54:15 +0000 (UTC) (envelope-from kostikbel@gmail.com) Authentication-Results: mx1.freebsd.org; none Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.17.1/8.17.1) with ESMTPS id 32NKs9Gw028423 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Thu, 23 Mar 2023 22:54:12 +0200 (EET) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua 32NKs9Gw028423 Received: (from kostik@localhost) by tom.home (8.17.1/8.17.1/Submit) id 32NKs75t028422; Thu, 23 Mar 2023 22:54:07 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Thu, 23 Mar 2023 22:54:07 +0200 From: Konstantin Belousov To: Mateusz Guzik Cc: sgk@troutmask.apl.washington.edu, Matthias Andree , freebsd-hackers@freebsd.org Subject: Re: Periodic rant about SCHED_ULE Message-ID: References: <8173cc7e-e934-dd5c-312a-1dfa886941aa@FreeBSD.org> <8cfdb951-9b1f-ecd3-2291-7a528e1b042c@m5p.com> 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=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FORGED_GMAIL_RCVD,FREEMAIL_FROM, NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=4.0.0 X-Spam-Checker-Version: SpamAssassin 4.0.0 (2022-12-14) on tom.home X-Rspamd-Queue-Id: 4PjHdM5j3Dz4765 X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:6939, ipnet:2001:470::/32, country:US] X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-ThisMailContainsUnwantedMimeParts: N On Thu, Mar 23, 2023 at 05:42:22PM +0100, Mateusz Guzik wrote: > On 3/23/23, Konstantin Belousov wrote: > > On Thu, Mar 23, 2023 at 04:15:21AM +0100, Mateusz Guzik wrote: > >> So I also ran the following setup: 8 core vm doing -j 8 buildkernel, > >> while 8 nice -n 20 processes are cpu-bound. After the build ends > >> workers report how many ops they did in that time. > > Why nice? Did you tried with the idle class instead? > > > > The original message reported numbers with -n 20 and it is not > particularly unusual. I do not think we should target this level of feature compatibility with the historic behavior. nice -20 was not guaranteed to behave the way it is requested in this thread ("only use CPU when no other threads are runnable"). Instead, it is the declared behavior of the idle class. If idle class is broken, then it is indeed should be fixed. But not nice -20, IMO.