From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from picard.linux.it (picard.linux.it [213.254.12.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B1555CA1010 for ; Fri, 5 Sep 2025 07:31:53 +0000 (UTC) Received: from picard.linux.it (localhost [IPv6:::1]) by picard.linux.it (Postfix) with ESMTP id 1F7553CD4DF for ; Fri, 5 Sep 2025 09:31:52 +0200 (CEST) Received: from in-7.smtp.seeweb.it (in-7.smtp.seeweb.it [IPv6:2001:4b78:1:20::7]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (secp384r1)) (No client certificate requested) by picard.linux.it (Postfix) with ESMTPS id 3BF7B3CD4D1 for ; Fri, 5 Sep 2025 09:31:36 +0200 (CEST) Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2a07:de40:b251:101:10:150:64:1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by in-7.smtp.seeweb.it (Postfix) with ESMTPS id 8421A200997 for ; Fri, 5 Sep 2025 09:31:34 +0200 (CEST) Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (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) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 003BE4D8A2; Fri, 5 Sep 2025 07:31:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1757057493; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=pvta3/lRbYsG52cW1BgeyW/O/4y3oOJi0BrPRgcZZTI=; b=DVdPwqztKQGlWlNisZ9kNkG0MOKfQxzG7w998XJQ6K47ddTTY1bu0Xqsl09OklUruZ9eIj UyK1oJ+vb1IEQIr3r3ff2vYeUPgpa+/BMLjEjJ0twA4wDNFSDyS2uhKpqRVu2epWfVBgnl rwBCXtJl2A9pqsu1sEbw+KqaRGvh/rs= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1757057493; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=pvta3/lRbYsG52cW1BgeyW/O/4y3oOJi0BrPRgcZZTI=; b=5wFDpO7fYqIA9ynvkoX98GJu5fn3tyF1C2Hy+SsyKWMgANaWYl9+CG7C+dK7Rg7dp75UMf QALH9UDmriaCziBQ== Authentication-Results: smtp-out1.suse.de; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=DVdPwqzt; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=5wFDpO7f DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1757057493; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=pvta3/lRbYsG52cW1BgeyW/O/4y3oOJi0BrPRgcZZTI=; b=DVdPwqztKQGlWlNisZ9kNkG0MOKfQxzG7w998XJQ6K47ddTTY1bu0Xqsl09OklUruZ9eIj UyK1oJ+vb1IEQIr3r3ff2vYeUPgpa+/BMLjEjJ0twA4wDNFSDyS2uhKpqRVu2epWfVBgnl rwBCXtJl2A9pqsu1sEbw+KqaRGvh/rs= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1757057493; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=pvta3/lRbYsG52cW1BgeyW/O/4y3oOJi0BrPRgcZZTI=; b=5wFDpO7fYqIA9ynvkoX98GJu5fn3tyF1C2Hy+SsyKWMgANaWYl9+CG7C+dK7Rg7dp75UMf QALH9UDmriaCziBQ== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (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) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id C231D13306; Fri, 5 Sep 2025 07:31:32 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id zT6rLtSRumioCAAAD6G6ig (envelope-from ); Fri, 05 Sep 2025 07:31:32 +0000 Date: Fri, 5 Sep 2025 09:31:27 +0200 From: Petr Vorel To: Li Wang , Cyril Hrubis , ltp@lists.linux.it, Andrea Cervesato , Chunyu Hu Message-ID: <20250905073127.GA16065@pevik> References: <20250904102609.133359-1-liwang@redhat.com> <20250904110018.GA56668@pevik> <20250905070312.GA4185@pevik> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20250905070312.GA4185@pevik> X-Spamd-Result: default: False [-3.71 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_RHS_NOT_FQDN(0.50)[]; HAS_REPLYTO(0.30)[pvorel@suse.cz]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; MIME_TRACE(0.00)[0:+]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FUZZY_RATELIMITED(0.00)[rspamd.com]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:replyto,suse.cz:dkim,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:104:10:150:64:97:from,2a07:de40:b281:106:10:150:64:167:received]; RCVD_VIA_SMTP_AUTH(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; DKIM_TRACE(0.00)[suse.cz:+]; MISSING_XM_UA(0.00)[]; REPLYTO_EQ_FROM(0.00)[] X-Rspamd-Queue-Id: 003BE4D8A2 X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Virus-Scanned: clamav-milter 1.0.7 at in-7.smtp.seeweb.it X-Virus-Status: Clean Subject: Re: [LTP] [PATCH v2] sched_football: synchronize with kickoff flag to reduce skew X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Petr Vorel Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ltp-bounces+ltp=archiver.kernel.org@lists.linux.it Sender: "ltp" > Hi all, > ... > > Checking the configurations of the stock kernel and the real-time > > kernel, the stock kernel uses "CONFIG_PREEMPT_VOLUNTARY=y," > > which only provides voluntary preemption. > Yes, CONFIG_PREEMPT_VOLUNTARY=y is in all mainline defconfigs > (arch/*/configs/*_defconfig). Therefore we have it in our Tumbleweed (6.16.3-1) > and in upcoming SLES16 (6.12 based). SLE15-SP7 (6.4 based) use > CONFIG_PREEMPT_NONE=y instead. > Looking at the history It works well on all archs, we just recently had a > problem with ppc64le hmc on SLE16 (regular ppc64le works). Later I'll check > history of older SLES versions. > And most importantly I'll try to run manually with -i (more stress test). > > This preemption model is designed to strike a balance between throughput > > and latency. It only allows the kernel to be preempted at specific, well > > defined > > "safe points," potentially resulting in long, unbounded latencies. > > However, the sched_football test was most likely designed to measure or > > stress-test the deterministic, low-latency scheduling behavior that is > > characteristic of real-time (RT) kernel. > > So, I tend to believe the test's failure on the stock kernel is acceptable. > > And, by the way, what does the SUSE kernel configuration look like? > > # grep CONFIG_PREEMPT /boot/config-6.12.0-55.29.1.el10_0.x86_64 > > CONFIG_PREEMPT_BUILD=y > > CONFIG_PREEMPT_VOLUNTARY=y > > # CONFIG_PREEMPT is not set > > # CONFIG_PREEMPT_RT is not set > > CONFIG_PREEMPT_COUNT=y > > CONFIG_PREEMPTION=y > > CONFIG_PREEMPT_DYNAMIC=y > > CONFIG_PREEMPT_RCU=y > > CONFIG_PREEMPT_NOTIFIERS=y > > (^ I built my v6.17-rc4 with this config too) > /boot/config-6.12.0-160000.4-default # Tumbleweed x68_64 > CONFIG_PREEMPT_BUILD=y > # CONFIG_PREEMPT_NONE is not set > CONFIG_PREEMPT_VOLUNTARY=y > # CONFIG_PREEMPT is not set > # CONFIG_PREEMPT_LAZY is not set > # CONFIG_PREEMPT_RT is not set > CONFIG_PREEMPT_COUNT=y > CONFIG_PREEMPTION=y > CONFIG_PREEMPT_DYNAMIC=y > CONFIG_PREEMPT_RCU=y > CONFIG_PREEMPT_NOTIFIERS=y > # CONFIG_PREEMPT_TRACER is not set > CONFIG_PREEMPTIRQ_DELAY_TEST=m > Upcoming SLE16 is similar to Tumbleweed. > /boot/config-6.4.0-150700.714.ga8e7017-default # SLE15-SP7 x86_64 RT > CONFIG_PREEMPT_BUILD=y > CONFIG_PREEMPT_NONE=y > # CONFIG_PREEMPT_VOLUNTARY is not set > # CONFIG_PREEMPT is not set > # CONFIG_PREEMPT_RT is not set > CONFIG_PREEMPT_COUNT=y > CONFIG_PREEMPTION=y > CONFIG_PREEMPT_DYNAMIC=y > CONFIG_PREEMPT_RCU=y > CONFIG_PREEMPT_NOTIFIERS=y > # CONFIG_PREEMPT_TRACER is not set > CONFIG_PREEMPTIRQ_DELAY_TEST=m > /boot/config-6.4.0-150700.5-rt # SLE15-SP7 x86_64 RT > CONFIG_PREEMPT_LAZY=y > # CONFIG_PREEMPT_NONE is not set > # CONFIG_PREEMPT_VOLUNTARY is not set > # CONFIG_PREEMPT is not set > CONFIG_PREEMPT_RT=y > CONFIG_PREEMPT_COUNT=y > CONFIG_PREEMPTION=y > CONFIG_PREEMPT_RCU=y > CONFIG_PREEMPT_NOTIFIERS=y > # CONFIG_PREEMPT_TRACER is not set > CONFIG_PREEMPTIRQ_DELAY_TEST=m And looking on some other distros, e.g. Debian had CONFIG_PREEMPT_VOLUNTARY=y on 6.12.38+deb13 (from recently released stable Debian 13 trixie), but they changed it to CONFIG_PREEMPT_LAZY=y in 6.16.3+deb14 (for upcoming Debian forky (testing) - in devel for now). I would expect that setup for RT kernel. > Kind regards, > Petr > > # grep CONFIG_PREEMPT /boot/config-6.12.0-55.31.1.el10_0.x86_64+rt > > CONFIG_PREEMPT_BUILD=y > > CONFIG_PREEMPT=y > > CONFIG_PREEMPT_RT=y > > CONFIG_PREEMPT_COUNT=y > > CONFIG_PREEMPTION=y > > # CONFIG_PREEMPT_DYNAMIC is not set > > CONFIG_PREEMPT_RCU=y > > CONFIG_PREEMPT_NOTIFIERS=y I suppose this RT kernel has CONFIG_PREEMPT_LAZY=y, right? Kind regards, Petr -- Mailing list info: https://lists.linux.it/listinfo/ltp