From nobody Sat Nov 15 11:09:56 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1753115107; cv=none; d=zohomail.com; s=zohoarc; b=CMLxqDe+lQAfuWHDKvPcX2E0C3ntQC+qfRecTp/bvOpmG8XVwAE0ImeySsZ1qPZEM58Q7AwaLja+mHA/mE5EeiWlo04duhnE9k/9Kur2XUSjX4hFvlsxcNuCTTPOCIdcje4heuWgEkTbIWwvUuQdTUKM+umZlsRfYT/B0muWfAs= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1753115107; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=PeaxLgyiIYKj0kt5yg0H9AiCj069c/p8og5RfRh37nA=; b=aNWoigLHqtTBnZ3k1J/eNtfq+G6gm2wmO1hWgm2TirSn7RPI/30vHtXYJq7Cqk2/kAPzv41Svx0D/sfrX5ffQesYHyHIs9UY6/wF8VJ/AFS7AzKDTWzABwvVWd7DDkXLMgp1cX0V4AcqhLAp2PzM7Pd810L/VndltM3JUaFQGSE= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1753115107952227.88890429148796; Mon, 21 Jul 2025 09:25:07 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1udtIz-0005Gf-Kq; Mon, 21 Jul 2025 12:23:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1udtIC-0003YC-JM for qemu-devel@nongnu.org; Mon, 21 Jul 2025 12:23:08 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1udtI9-0001Q9-T0 for qemu-devel@nongnu.org; Mon, 21 Jul 2025 12:23:08 -0400 Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-661-DI98qf95OJ-sz9uemG2XAw-1; Mon, 21 Jul 2025 12:23:02 -0400 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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 mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E46ED18002B6; Mon, 21 Jul 2025 16:23:00 +0000 (UTC) Received: from corto.redhat.com (unknown [10.45.224.19]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 74FE5195608D; Mon, 21 Jul 2025 16:22:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1753114984; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PeaxLgyiIYKj0kt5yg0H9AiCj069c/p8og5RfRh37nA=; b=UzqVyQdiLYrZycS71pQuyKhxlbTjK+yrJhaJYRZPpq2y2FLuEOvUmFUDqjBipaCcS3RuQt iCcdkFPJQ9dMWVm6T3UodFZf3PgXkE1SsN2ygUC7H66hp6kJNUbGGXKa8XIpCtN2loVNUU eLqeKFudaNFQmjPeU+yPJc3pZuYHQ8M= X-MC-Unique: DI98qf95OJ-sz9uemG2XAw-1 X-Mimecast-MFC-AGG-ID: DI98qf95OJ-sz9uemG2XAw_1753114981 From: =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= To: qemu-devel@nongnu.org Cc: Nicholas Piggin , Daniel Henrique Barboza , Glenn Miles , Michael Kowal , Caleb Schlossin , Gautam Menghani , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= Subject: [PULL 08/50] ppc/xive2: Use fair irq target search algorithm Date: Mon, 21 Jul 2025 18:21:51 +0200 Message-ID: <20250721162233.686837-9-clg@redhat.com> In-Reply-To: <20250721162233.686837-1-clg@redhat.com> References: <20250721162233.686837-1-clg@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=clg@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.926, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1753115108989116600 From: Glenn Miles The current xive algorithm for finding a matching group vCPU target always uses the first vCPU found. And, since it always starts the search with thread 0 of a core, thread 0 is almost always used to handle group interrupts. This can lead to additional interrupt latency and poor performance for interrupt intensive work loads. Changing this to use a simple round-robin algorithm for deciding which thread number to use when starting a search, which leads to a more distributed use of threads for handling group interrupts. [npiggin: Also round-robin among threads, not just cores] Signed-off-by: Glenn Miles Reviewed-by: Nicholas Piggin Reviewed-by: Glenn Miles Reviewed-by: Michael Kowal Reviewed-by: Caleb Schlossin Tested-by: Gautam Menghani Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-9-npiggin@gm= ail.com Signed-off-by: C=C3=A9dric Le Goater --- hw/intc/pnv_xive2.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/hw/intc/pnv_xive2.c b/hw/intc/pnv_xive2.c index ec247ce48ff7..25dc8a372d2f 100644 --- a/hw/intc/pnv_xive2.c +++ b/hw/intc/pnv_xive2.c @@ -643,13 +643,18 @@ static int pnv_xive2_match_nvt(XivePresenter *xptr, u= int8_t format, int i, j; bool gen1_tima_os =3D xive->cq_regs[CQ_XIVE_CFG >> 3] & CQ_XIVE_CFG_GEN1_TIMA_OS; + static int next_start_core; + static int next_start_thread; + int start_core =3D next_start_core; + int start_thread =3D next_start_thread; =20 for (i =3D 0; i < chip->nr_cores; i++) { - PnvCore *pc =3D chip->cores[i]; + PnvCore *pc =3D chip->cores[(i + start_core) % chip->nr_cores]; CPUCore *cc =3D CPU_CORE(pc); =20 for (j =3D 0; j < cc->nr_threads; j++) { - PowerPCCPU *cpu =3D pc->threads[j]; + /* Start search for match with different thread each call */ + PowerPCCPU *cpu =3D pc->threads[(j + start_thread) % cc->nr_th= reads]; XiveTCTX *tctx; int ring; =20 @@ -694,6 +699,15 @@ static int pnv_xive2_match_nvt(XivePresenter *xptr, ui= nt8_t format, if (!match->tctx) { match->ring =3D ring; match->tctx =3D tctx; + + next_start_thread =3D j + start_thread + 1; + if (next_start_thread >=3D cc->nr_threads) { + next_start_thread =3D 0; + next_start_core =3D i + start_core + 1; + if (next_start_core >=3D chip->nr_cores) { + next_start_core =3D 0; + } + } } count++; } --=20 2.50.1