From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 A0BF314373F for ; Wed, 7 Aug 2024 19:11:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723057894; cv=none; b=WQP6U+0ppkRGqpjlvA/PChinMAbCuxaS5C7v0t1uvAhoYeCBdlRWAgPCn1yyLUjjYGyOwZvNza0Vaz6yif9v7OSfCTShsjwaSXKsqKCwVknhEFxelt1Jocy6x1Z9/UcdTHHD+vkgIEXdOb8f/T2QGsA5P4FZVmy+gopVMBwHqr8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723057894; c=relaxed/simple; bh=boXeYOgmsSI7jQLPP3rC9V5QHVs6M7/EC/tK6josOQk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nm8Ggjvt/lYqeR5s8cPFizaktVeGZSys4AZDL7DxIGDoup6eZ3JGjIm4iXiFMBO9aiWmU56aW3OaQ+UvXU3kPhAHiVmlS3GYl+92hTv27COZuNiqgTpf7uaVElUMhNzKrrtl5Ts3l0Lf5Ex0I/54Zd1O7Kn4Qs1iU4XfApGDFBo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=O0TyrD9G; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="O0TyrD9G" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1723057889; 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: in-reply-to:in-reply-to:references:references; bh=pJygTm4A1Krh0SDaiBDWtmj5UAGZGfoNSdvtHXlv38I=; b=O0TyrD9GAB+NjGihjNr+ku0iBRmfZZZ7vkT6rHUPQGOrmPnMvQlRS/znv3LavgIok3lyjS iPwMdBo758WooWGKURXUVjrENeJ3vjdDfW3JPJfn+YBbOlDMChr7idef2HfLdqYqI6q4eE l/k11UxnfoZ29WA25pLSZqw0MJ7fv1E= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-422-a8dQgaBMNuKkAzi5nzscvw-1; Wed, 07 Aug 2024 15:11:24 -0400 X-MC-Unique: a8dQgaBMNuKkAzi5nzscvw-1 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-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id DC2DE1944B2F; Wed, 7 Aug 2024 19:11:19 +0000 (UTC) Received: from pauld.westford.csb (unknown [10.22.33.13]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8A52319560A3; Wed, 7 Aug 2024 19:11:10 +0000 (UTC) Date: Wed, 7 Aug 2024 15:11:08 -0400 From: Phil Auld To: Tejun Heo Cc: torvalds@linux-foundation.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org, joshdon@google.com, brho@google.com, pjt@google.com, derkling@google.com, haoluo@google.com, dvernet@meta.com, dschatzberg@meta.com, dskarlat@cs.cmu.edu, riel@surriel.com, changwoo@igalia.com, himadrics@inria.fr, memxor@gmail.com, andrea.righi@canonical.com, joel@joelfernandes.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH 09/30] sched_ext: Implement BPF extensible scheduler class Message-ID: <20240807191004.GB47824@pauld.westford.csb> References: <20240618212056.2833381-1-tj@kernel.org> <20240618212056.2833381-10-tj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240618212056.2833381-10-tj@kernel.org> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Hi Tejun, On Tue, Jun 18, 2024 at 11:17:24AM -1000 Tejun Heo wrote: > Implement a new scheduler class sched_ext (SCX), which allows scheduling > policies to be implemented as BPF programs to achieve the following: > I looks like this is slated for v6.12 now? That would be good. My initial experimentation with scx has been positive. I just picked one email, not completely randomly. > - Both enable and disable paths are a bit complicated. The enable path > switches all tasks without blocking to avoid issues which can arise from > partially switched states (e.g. the switching task itself being starved). > The disable path can't trust the BPF scheduler at all, so it also has to > guarantee forward progress without blocking. See scx_ops_enable() and > scx_ops_disable_workfn(). I think, from a supportability point of view, there needs to be a pr_info, at least, in each of these places, enable and disable, with the name of the scx scheduler. It looks like there is at least a pr_error for when one gets ejected due to misbehavior. But there needs to be a record of when such is loaded and unloaded. Thoughts? Cheers, Phil