From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail17.out.titan.email (mail17.out.titan.email [3.64.226.211]) (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 BA12A32C33C for ; Wed, 12 Nov 2025 12:50:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=3.64.226.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762951838; cv=none; b=eHj9tSuwgzYXRfAtnQY4Vdm3qXAHdDM7NYXOarAS0+Ui9XdjdE6p9aWJ2UtbeP1VwYjCg6HYAGpVS2b1H0ir2yiKPlSo+sgPia+eXBZZ6dmZwq2attXJZIITTQA8XSAd5F9BT8iK7UpYkYxFySfiK2EPYulxUVxvOkctvAZidlk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762951838; c=relaxed/simple; bh=E5uUb7+fbX62Zh2Uz+APdCR0qyuD2bfcfohAbeZ7Yr4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=hHptK0x0kjTw7mY0tbfavZPafSPKlNiJmfzOlz4tIrpbhhmeS+BVlEs5YHc4MFGlUQBxI/t//h914N+RtNT8rQkXxpxDEu/wh0I0FxL7rGb74BpgG4fxp17mko1fyFKvbFfU6suKDIUNds2SJS94riL7umNaFo8KD+jeKkSwHaI= 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=IBN/EQeB; arc=none smtp.client-ip=3.64.226.211 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="IBN/EQeB" Received: from localhost (localhost [127.0.0.1]) by smtp-out0101.titan.email (Postfix) with ESMTP id 4d62g634Jtz4vxN; Wed, 12 Nov 2025 12:25:38 +0000 (UTC) DKIM-Signature: a=rsa-sha256; bh=1ha9FVX34PW7qq5iLHUavAVRdbNPoP4zzhmRO+QDUeY=; c=relaxed/relaxed; d=techsingularity.net; h=mime-version:subject:to:from:cc:date:message-id:from:to:cc:subject:date:message-id:in-reply-to:reply-to:references; q=dns/txt; s=titan1; t=1762950338; v=1; b=IBN/EQeBpjZssXUFnTUZFCa8q7TUhF3SWrBsezkJujqPqzfYf4Z4JNYge1HmRd54XtHFLuYx 6i75WHhJtF7/gf5VjCW5ueLgPkbsNr9csFTPWhMJ8G15haejHu4GdbSn0ptno/ULsX3GYv8fxqZ oETrZVImnq6NcO++b+yj4bXo= 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 4d62g55m6nz4vxG; Wed, 12 Nov 2025 12:25:37 +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 , Madadi Vineeth Reddy , linux-kernel@vger.kernel.org, Mel Gorman Subject: [PATCH 0/2 v5] Reintroduce NEXT_BUDDY for EEVDF Date: Wed, 12 Nov 2025 12:25:19 +0000 Message-ID: <20251112122521.1331238-1-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: 1762950338277317561.1240.4361959595493664707@prod-euc1-smtp-out1002. X-CMAE-Score: 0 X-CMAE-Analysis: v=2.4 cv=d4QPyQjE c=1 sm=1 tr=0 ts=69147cc2 a=SAet2ifMzLisiRUXZwfs3w==:117 a=SAet2ifMzLisiRUXZwfs3w==:17 a=CEWIc4RMnpUA:10 a=7qnGvtjcerDTETLpIb4A:9 Changes since v4 o Splitout decisions into separate functions (peterz) o Flow clarity (peterz) 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. Mel Gorman (2): sched/fair: Enable scheduler feature NEXT_BUDDY sched/fair: Reimplement NEXT_BUDDY to align with EEVDF goals kernel/sched/fair.c | 152 ++++++++++++++++++++++++++++++++++------ kernel/sched/features.h | 2 +- 2 files changed, 131 insertions(+), 23 deletions(-) -- 2.51.0