From nobody Mon Feb 9 21:19:34 2026 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) (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 2B95A42056 for ; Sun, 26 Jan 2025 10:16:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.60.130.6 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737886599; cv=none; b=IuVksndBFZFi13MhqS1/IMGFXyKwe2zDduTdYXoAXWr9/e589GvczYX6IpebFVZ/5WLycRbX7TFa7uD2vBhAqnOi4Eewjg6LwpG4QCScxl8d1sei1aGn9V9Eih+mJiOjD7DFcqDxo6NEaijpJLI2EeWOq9tQrga6T5m8s2kSQes= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737886599; c=relaxed/simple; bh=hRytXuPdZ4eY/Vi7LG+Z66mcYe0k8R44dTBELteGLmQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Nl11qniGp4UFK5zcTXUN0c6G8xKkV+R+Ik8FIF267OSqwIhWrbV9Z+gY6ilHej3OAgpTOgEklt7GIlK6khBCNfIONYsWuZHo9nZpm51C/iIC5KXVnGqwnf7VfCTDTgWSFqNTEVNpkZE40QBZGxV7e6nlpPYxzHOcjOlYEKOw9EU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=Qk367XkY; arc=none smtp.client-ip=178.60.130.6 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="Qk367XkY" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=sPqJ9e0DzmFdhShg1je6pjpQv6coY3BIeaACfDk8MII=; b=Qk367XkYQD0IIKIdWj4zITtX1B z7Xvn4chig6AN0UrdAyt0PT1AAZKa1JqNz5kxMepKsU0F+XmXMXBIVmoj0EbnJCen5NnRUjZKQSB3 e/Gc/jpKildpNK3neDp5VdS9/7x6VJTJzcNIkrkHbV6jDtyVZt6CLnS+JHQBRjGiihWwjbab5IDyQ kUH5dY/vcjdHjCGNJRbk6bnzSG5MReuQ7J05GzLxMdqg2vvHjTTz1+7r7HlUtZi5T6IYxmrJFz/Ys 5E75oSYYrktM+LpFLIH3D+1Dfh//2G+HGb8kkGRGA6nN0slS5jvJuYtRCfeFwug3wKTxiSA007Wjr wnQWhS1w==; Received: from [58.29.143.236] (helo=localhost) by fanzine2.igalia.com with utf8esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1tbzgt-002lj8-QT; Sun, 26 Jan 2025 11:16:32 +0100 From: Changwoo Min To: tj@kernel.org, void@manifault.com, arighi@nvidia.com Cc: kernel-dev@igalia.com, linux-kernel@vger.kernel.org, Changwoo Min Subject: [PATCH v2 03/11] sched_ext: Add an event, SELECT_CPU_FALLBACK Date: Sun, 26 Jan 2025 19:16:06 +0900 Message-ID: <20250126101614.232388-4-changwoo@igalia.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250126101614.232388-1-changwoo@igalia.com> References: <20250126101614.232388-1-changwoo@igalia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a core event, SELECT_CPU_FALLBACK, which represents how many times ops.select_cpu() returns a CPU that the task can't use. __scx_add_event() is used since the caller holds a p->pi_lock, so the preemption has already been disabled. Signed-off-by: Changwoo Min --- kernel/sched/ext.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index dbf659d593a3..727b1f8b623e 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -1462,6 +1462,11 @@ static struct task_struct *scx_task_iter_next_locked= (struct scx_task_iter *iter) * Collection of event counters. Event types are placed in descending orde= r. */ struct scx_event_stats { + /* + * If ops.select_cpu() returns a CPU which can't be used by the task, + * the core scheduler code silently picks a fallback CPU. + */ + u64 SELECT_CPU_FALLBACK; }; =20 /* @@ -3663,6 +3668,10 @@ static int select_task_rq_scx(struct task_struct *p,= int prev_cpu, int wake_flag cpu =3D SCX_CALL_OP_TASK_RET(SCX_KF_ENQUEUE | SCX_KF_SELECT_CPU, select_cpu, p, prev_cpu, wake_flags); *ddsp_taskp =3D NULL; + + if (unlikely(!is_cpu_allowed(p, cpu))) + __scx_add_event(SELECT_CPU_FALLBACK, 1); + if (ops_cpu_valid(cpu, "from ops.select_cpu()")) return cpu; else @@ -5482,6 +5491,7 @@ static void scx_dump_state(struct scx_exit_info *ei, = size_t dump_len) dump_line(&s, "--------------"); =20 scx_bpf_event_stats(&events, sizeof(events)); + scx_dump_event(s, &events, SELECT_CPU_FALLBACK); =20 if (seq_buf_has_overflowed(&s) && dump_len >=3D sizeof(trunc_marker)) memcpy(ei->dump + dump_len - sizeof(trunc_marker), @@ -7810,6 +7820,7 @@ __bpf_kfunc void scx_bpf_event_stats(struct scx_event= _stats *events, memset(&e_sys, 0, sizeof(e_sys)); for_each_possible_cpu(cpu) { e_cpu =3D per_cpu_ptr(&event_stats_cpu, cpu); + scx_agg_event(&e_sys, e_cpu, SELECT_CPU_FALLBACK); } =20 /* --=20 2.48.1