From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail46.out.titan.email (mail46.out.titan.email [3.66.115.72]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4E66F2FF64C for ; Mon, 3 Nov 2025 11:05:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=3.66.115.72 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762167914; cv=none; b=i7nExYrEph9miw2V/U3ChnidU7ISfhrIGFA2w/ETA4pMiDGIYSWWhMnPYHFwe6IPyuKiGTt8RKhYDp/WEaxrwZf4UqqnKEZ//SLwGmYkblOsC9g5yyCr/jyEHWrMRmihp0fltdRBoDalAFmDLg0KlorXrWhsGBhGTE/lHOMj7VA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762167914; c=relaxed/simple; bh=W18v5yG+KjN2PnLk8ZAPuo5ABAhAcfytXJXVDWdlKrU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=nILUfmf7ioxtKwWnNRQIdVICG28EH7YnZyaRx5RKYWgm1SGads/PGFL2NE+FkUx4N69DI+kgnthQ/metnQPSKeBBIA6nyqm67+tNv4iZPaRapDQOCR2a6yGW3Yc4vgw9aZYRw4nvORS9wNcfSKGyGYbI1sfJvWN1QhhmPxu9+60= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net; spf=pass smtp.mailfrom=techsingularity.net; dkim=pass (1024-bit key) header.d=techsingularity.net header.i=@techsingularity.net header.b=ej472WrL; arc=none smtp.client-ip=3.66.115.72 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=techsingularity.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=techsingularity.net header.i=@techsingularity.net header.b="ej472WrL" Received: from localhost (localhost [127.0.0.1]) by smtp-out0101.titan.email (Postfix) with ESMTP id 4d0TJG4GY1z4vxR; Mon, 3 Nov 2025 11:05:02 +0000 (UTC) DKIM-Signature: a=rsa-sha256; bh=VAkNd431g2Hrdyc75Iro8jdBi3HN/YvW1jrWVnVfBS0=; c=relaxed/relaxed; d=techsingularity.net; h=message-id:subject:date:to:mime-version:cc:from:from:to:cc:subject:date:message-id:in-reply-to:reply-to:references; q=dns/txt; s=titan1; t=1762167902; v=1; b=ej472WrLeRw8X9AOLLi0GZk9gX3d4DDCv1djOvdNwQoSyxnVnZ5gWM8BAIxb9a12XWGMzTL0 AxcQkcVlN2yaQOMeaMm/Ad9lgFmb/yG6TP5Rn1KBUivalyonUQrbM4ARXhAyurqyX5KJvRgYcQY 0K2JPYZSHX4asNhRcyLZ/aik= Received: from morpheus.112glenside.lan (ip-84-203-16-53.broadband.digiweb.ie [84.203.16.53]) by smtp-out0101.titan.email (Postfix) with ESMTPA id 4d0TJF3vzFz4vxX; Mon, 3 Nov 2025 11:05:00 +0000 (UTC) Feedback-ID: :mgorman@techsingularity.net:techsingularity.net:flockmailId From: Mel Gorman To: Peter Zijlstra Cc: Ingo Molnar , Juri Lelli , Dietmar Eggemann , Valentin Schneider , Chris Mason , linux-kernel@vger.kernel.org, Mel Gorman Subject: [PATCH 0/2 v4] Reintroduce NEXT_BUDDY for EEVDF Date: Mon, 3 Nov 2025 11:04:43 +0000 Message-ID: <20251103110445.3503887-1-mgorman@techsingularity.net> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-F-Verdict: SPFVALID X-Titan-Src-Out: 1762167902397498265.2237.1991502224486795250@prod-euc1-smtp-out1002. X-CMAE-Score: 0 X-CMAE-Analysis: v=2.4 cv=AMAIbF65 c=1 sm=1 tr=0 ts=69088c5e a=SAet2ifMzLisiRUXZwfs3w==:117 a=SAet2ifMzLisiRUXZwfs3w==:17 a=CEWIc4RMnpUA:10 a=7qnGvtjcerDTETLpIb4A:9 Changes since v3 o Place new code near first consumer (peterz) o Separate between PREEMPT_SHORT and NEXT_BUDDY (peterz) o Naming and code flow clarity (peterz) o Restore slice protection (peterz) Changes since v2 o Review feedback applied from Prateek I've been chasing down a number of schedule issues recently like many others and found they were broadly grouped as 1. Failure to boost CPU frequency with powersave/ondemand governors 2. Processors entering idle states that are too deep 3. Differences in wakeup latencies for wakeup-intensive workloads Adding topology into account means that there is a lot of machine-specific behaviour which may explain why some discussions recently have reproduction problems. Nevertheless, the removal of LAST_BUDDY and NEXT_BUDDY being disabled has an impact on wakeup latencies. This series enables NEXT_BUDDY and may select a wakee if it's eligible to run even though other unrelated tasks may have an earlier deadline. kernel/sched/fair.c | 145 ++++++++++++++++++++++++++++++++++------ kernel/sched/features.h | 2 +- 2 files changed, 124 insertions(+), 23 deletions(-) -- 2.51.0