From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 004.mia.mailroute.net (004.mia.mailroute.net [199.89.3.7]) (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 F3CDE623; Sun, 23 Mar 2025 12:36:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=199.89.3.7 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742733376; cv=none; b=K28RyGGbIDv+ZV2f0EgxijTTT1l3zdi5RGBLi40k5aNezyQeHHPMLQqg6+JobfTOZbFQ0NgFyVGNElKZPudgewILWWlVTK+DiabCsQvz/Ge/P5+SoXBvXtSbcWfOWzm0AI44yx6+/EeQG/qqMpsfh6MrMii77IqidDQmMHRvlpc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742733376; c=relaxed/simple; bh=cKnmb/AvRSbteASF5DT+ty/21aXMVv19VOgr9QzltMs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=cP5NurDTI1MoL5dqt7rmnbe3Bf541yaSzqpKVUzPoEpynG1UzgLyXYZLng7p7zvLaH0dzmH1zLBu3hZmS78uD1gr7M4dX5Cz9YVqW/4Dexva5YAZ/DF5IdkSvetHeWoVSoUcNP+dEl9I1WgtGxPfSFH/Va0gkwcDj1/m4NjhGqw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org; spf=pass smtp.mailfrom=acm.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b=A5GWs8ZZ; arc=none smtp.client-ip=199.89.3.7 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=acm.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b="A5GWs8ZZ" Received: from localhost (localhost [127.0.0.1]) by 004.mia.mailroute.net (Postfix) with ESMTP id 4ZLFzD1Dqjzm0ytd; Sun, 23 Mar 2025 12:36:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=acm.org; h= content-transfer-encoding:content-type:content-type:in-reply-to :from:from:content-language:references:subject:subject :user-agent:mime-version:date:date:message-id:received:received; s=mr01; t=1742733366; x=1745325367; bh=5tj9iO/ST31ro8NtZXZ+WYzO 2KM6kAX7w53AjZ7Mg0A=; b=A5GWs8ZZ3fEVqp/IdS6gJ5ndHfUdUWDGXjSVadOm ULUDNHfTeBg63zQOC/FYqWafLEyyAuM3Acaon/qlwAwmofjkUL5leSzGQEXN4bfp WeJcisPT0KAPbeKZdB/55HMrN8u5xr/jwzLKUE+ozDsWc3cCxJOnvCU7Pgx2VhdT 5acN3hB2uASO90SyDR+xECFYnU7+e+XAhi/WOOc8UV5nhrk8hNZ7pYayDN7zx8FL ol/sdTCpYOQjem7jkiWyVzuQVGtdBVJkqMjD/+1LXwYaJrpJm28WeIN4ToORgdA4 /dIFh62l4lQ0i1AeUXXBP2LnlNa5+p1Aqie5zaD/JRTR1Q== X-Virus-Scanned: by MailRoute Received: from 004.mia.mailroute.net ([127.0.0.1]) by localhost (004.mia [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id dO7ADQ8zc2Rh; Sun, 23 Mar 2025 12:36:06 +0000 (UTC) Received: from [10.46.23.145] (unknown [156.39.10.100]) (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) (Authenticated sender: bvanassche@acm.org) by 004.mia.mailroute.net (Postfix) with ESMTPSA id 4ZLFz56LcHzm0pKT; Sun, 23 Mar 2025 12:36:00 +0000 (UTC) Message-ID: <1ae51ccc-66cc-4551-b649-2f5883e2f5a2@acm.org> Date: Sun, 23 Mar 2025 05:35:59 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] cpuidle: psd: add power sleep demotion prevention for fast I/O devices To: "King, Colin" , Christian Loehle , Jens Axboe , "Rafael J. Wysocki" , Daniel Lezcano , "linux-block@vger.kernel.org" , "linux-pm@vger.kernel.org" Cc: "linux-kernel@vger.kernel.org" References: <33882f284ac6e6d1ec766ca4bb2f3b88@intel.com> Content-Language: en-US From: Bart Van Assche In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/17/25 3:03 AM, King, Colin wrote: > This code is optional, one can enable it or disable it via the config option. Also, > even when it is built-in one can disable it by writing 0 to the sysfs file > /sys/devices/system/cpu/cpuidle/psd_cpu_lat_timeout_ms I'm not sure we need even more configuration knobs in sysfs. How are users expected to find this configuration option? How should they decide whether to enable or to disable it? Please take a look at this proposal and let me know whether this would solve the issue that you are looking into: "[LSF/MM/BPF Topic] Energy- Efficient I/O" (https://lore.kernel.org/linux-block/ad1018b6-7c0b-4d70- b845-c869287d3cf3@acm.org/). The only disadvantage of this approach compared to the cpuidle patch is that it requires RPM (runtime power management) to be enabled. Maybe I should look into modifying the approach such that it does not rely on RPM. Thanks, Bart.