From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qv1-f43.google.com (mail-qv1-f43.google.com [209.85.219.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1B4EA5C85 for ; Wed, 24 Jan 2024 02:59:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706065199; cv=none; b=G59nKG6sq5WrPV/9c0KnnKz0DkZ7PapufrcRSRvvyTMB9ZpmLfkfn6sXGoV4ZUuunZnTY0pw1/3wqSTuB0xj/2N7iA06iwlQ7c/Re2bSMt0t//bCzqpHSFRcQ9LNcDV7RqDgbm/NHCvhfoUvJt6ehrOd4jXWu5lzOsm4GTUNoX0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706065199; c=relaxed/simple; bh=fPXQ85z2dk4ZElnoHE7IKEGnCx5Zs8ywjvfrYfs+rnc=; h=Message-ID:Date:MIME-Version:To:From:Subject:Content-Type; b=mWSOH/gV2zI0oRVT739J28TMvy971fjSbneazdh/GEk1WKJT1eJWYassuWU7jgbCJPZy60XiG2xk53OSU49wsPIpyRTBl0MbT5u85tIqNfi+A0BUJFUOz0RL8E7SIsSIfJu5vWel43W2bz7+96UMmDU54ce+Q/p4PjMl0T8KciM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=joelfernandes.org; spf=pass smtp.mailfrom=joelfernandes.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b=uxJp/mVX; arc=none smtp.client-ip=209.85.219.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=joelfernandes.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=joelfernandes.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="uxJp/mVX" Received: by mail-qv1-f43.google.com with SMTP id 6a1803df08f44-6860ff3951aso19887336d6.1 for ; Tue, 23 Jan 2024 18:59:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1706065195; x=1706669995; darn=vger.kernel.org; h=content-transfer-encoding:subject:from:to:content-language :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to; bh=fPXQ85z2dk4ZElnoHE7IKEGnCx5Zs8ywjvfrYfs+rnc=; b=uxJp/mVXJYZvYcyZpHLegAgJr4hnfl3p5iCCF0HIeEWHV0RxLJXZsrU8SDHMibym+1 0efFBxpK2QZqQCEgUhX6WnKaOjiIgbysWrOE3pgw5jyVA3vE0C64T/DYrHnRWylKtHqw RWXTy5heNCT4ddFhbGBVrhPNlYYQtd33dLGNQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706065195; x=1706669995; h=content-transfer-encoding:subject:from:to:content-language :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=fPXQ85z2dk4ZElnoHE7IKEGnCx5Zs8ywjvfrYfs+rnc=; b=tNh9auYSd1UO5bXnYjZKP+hxzOqfOJqEFXinS1Bcrj79/V3w0H3LMAKiffAAuA8hb9 KnMemjyn7UdLb3XHiheGcsrgo9RzVZeXG62nsy50T4v1RLh03KE8Hgv2wlyp8y5/NnHu XugyAwmwUwwgGA4Ji4E/WmngYYcMOni0oa4wcVEBjfzN1rI5Ck7/fd5ftN0cw45rC7Au xKALfbHVzLMqO2PzxkX+eG3KdrowYwKtHcPD9NSvHPGc344uF2LjKhQ887hALFSNhJPk xzYCebXT0YMT5m5Pwpzk+Oe6nsMvu9JkJyYD6X42FyHbpH8NO/EMl7+zP7LW49ibWNwn rgFA== X-Gm-Message-State: AOJu0Yy8d6V8OblJ8gVq4gbhBamn8ZRvaoEG123tfsP79s5L5a+GLAYT TQpr/q+G+gz1cWYaH6ADat3s0RlIyJVNYCsIo/Agwr8oRVrDvUTfFcKGn5gQEknWozH7a7NL1GP 3 X-Google-Smtp-Source: AGHT+IG44QU/LDIhbmsiTW8NxQHUaWnDU30Dem3QjQRhFIOldFE7nmnnI4Pc+Ds9bCz6CkE8RcX4Lw== X-Received: by 2002:a05:6214:2a48:b0:686:261a:76a0 with SMTP id jf8-20020a0562142a4800b00686261a76a0mr2165811qvb.52.1706065195477; Tue, 23 Jan 2024 18:59:55 -0800 (PST) Received: from [10.5.0.2] ([45.88.220.198]) by smtp.gmail.com with ESMTPSA id qp19-20020a056214599300b0068688a2962fsm3018537qvb.29.2024.01.23.18.59.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Jan 2024 18:59:54 -0800 (PST) Message-ID: <653c2448-614e-48d6-af31-c5920d688f3e@joelfernandes.org> Date: Tue, 23 Jan 2024 21:59:50 -0500 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Content-Language: en-US To: bpf@vger.kernel.org, lsf-pc@lists.linux-foundation.org, David Vernet , Sean Christopherson , Vineeth Pillai , Steven Rostedt , Suleiman Souhlal From: Joel Fernandes Subject: [LSF/MM/BPF TOPIC] Implementing KVM vCPU Priority boosting via BPF Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit We should discuss a new approach for increasing KVM virtual CPU (vCPU) priority when guests need low latency. The last RFC posting [1] on this is thought to be too rigid and baking too much policy into the kernel. Incorporating complex policy logic directly into KVM seems problematic long-term for maintenance. Lets discuss leveraging BPF programs to offload more scheduling policy decisions to BPF / userspace. Specific issues to discuss: * Add support for enabling BPF programs to share memory and interface with guest. * Create a kernel function allowing BPF programs to call sched_setscheduler(), facilitating priority boosting. * UAPI concerns. * Challenges with loading BPF programs in guest userspace we don't control. [1] https://lore.kernel.org/all/20231214024727.3503870-1-vineeth@bitbyteword.org/