From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 746CD15D4; Fri, 9 Feb 2024 01:58:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707443924; cv=none; b=NWpJaLzMi/P0pDc5V4UOB0lJmCnIOyPiYd42eWuTXQIVWCkv7fV4PxaIzY5OCdfwE/ZJmWCLw8OTtZHdv5xkqa5f7tjmyQrGkyh51bJq2yUvR14Kl23m8zPnOUv2qPABByukgZQxK025er0snoqFVhUFisvFYiiih94DfKlMy8k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707443924; c=relaxed/simple; bh=fhyg5jBDizytO6x3hZXyQa4pHMLhM/GRB9tg0/a7aZE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=MCP+9xTxjmMNvxRvENPrzVz4kTNdaU7tBNiXoSJEHfQRsvoSXPvd6dbveSXQGkkJ7vVNpp2Co7OpbNIbcX17NPQgXEbkow7NalB5Nr7CP2cKMHLrUIk1Jjz/QhzGDkm173DeNtiDmIkH6A1rIq4rj8nxgrnvfZ69UF45F6zShjk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mwNkCvof; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mwNkCvof" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1481DC433C7; Fri, 9 Feb 2024 01:58:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1707443924; bh=fhyg5jBDizytO6x3hZXyQa4pHMLhM/GRB9tg0/a7aZE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=mwNkCvofzO6gMxI2qcdtN8md9csh2uCkP/J0eHFdHTB4dLVWyLHZ3aiYlQJM/jduZ +hryoxuATnyhBUk/vVVCkwJsVtM5o+K9SeXc33ObfsubUvnxZGA2bWHr0aA19uBPfV dYl5ozEtRoRfx35lUC9EOh99D57uk/k+w660bE0O3dHEJWEzQIIPW7k+dBY8OmSRqT IxriGWy0bd3IYLrE88cJMjkUjyHYbKtv0kBhyirD62VatmfDIu9cZzSivIO0mAdgwY 7aXkwrwgw9SvkzG5X7IKVcJa1psfjfaF4noxrt1HDpWD+q39x5noI7hsS3invtHjuE hvgT7gF8VQPPg== Message-ID: Date: Fri, 9 Feb 2024 10:58:40 +0900 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 3/3] block: introducing a bias over deadline's fifo_time Content-Language: en-US To: Zhaoyang Huang , Jens Axboe Cc: "zhaoyang.huang" , Peter Zijlstra , Ingo Molnar , Juri Lelli , Vincent Guittot , Yu Zhao , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, steve.kang@unisoc.com References: <20240208093136.178797-1-zhaoyang.huang@unisoc.com> <20240208093136.178797-3-zhaoyang.huang@unisoc.com> From: Damien Le Moal Organization: Western Digital Research In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 2/9/24 09:28, Zhaoyang Huang wrote: > On Fri, Feb 9, 2024 at 8:11 AM Jens Axboe wrote: >> >> On 2/8/24 5:02 PM, Zhaoyang Huang wrote: >>> On Fri, Feb 9, 2024 at 1:49?AM Jens Axboe wrote: >>>> >>>> On 2/8/24 2:31 AM, zhaoyang.huang wrote: >>>>> diff --git a/block/mq-deadline.c b/block/mq-deadline.c >>>>> index f958e79277b8..43c08c3d6f18 100644 >>>>> --- a/block/mq-deadline.c >>>>> +++ b/block/mq-deadline.c >>>>> @@ -15,6 +15,7 @@ >>>>> #include >>>>> #include >>>>> #include >>>>> +#include "../kernel/sched/sched.h" >>>>> >>>>> #include >>>>> >>>>> @@ -802,6 +803,7 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, >>>>> u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio); >>>>> struct dd_per_prio *per_prio; >>>>> enum dd_prio prio; >>>>> + int fifo_expire; >>>>> >>>>> lockdep_assert_held(&dd->lock); >>>>> >>>>> @@ -840,7 +842,9 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, >>>>> /* >>>>> * set expire time and add to fifo list >>>>> */ >>>>> - rq->fifo_time = jiffies + dd->fifo_expire[data_dir]; >>>>> + fifo_expire = task_is_realtime(current) ? dd->fifo_expire[data_dir] : >>>>> + CFS_PROPORTION(current, dd->fifo_expire[data_dir]); >>>>> + rq->fifo_time = jiffies + fifo_expire; >>>>> insert_before = &per_prio->fifo_list[data_dir]; >>>>> #ifdef CONFIG_BLK_DEV_ZONED >>>>> /* >>>> >>>> Hard pass on this blatant layering violation. Just like the priority >>>> changes, this utterly fails to understand how things are properly >>>> designed. >>> IMHO, I don't think this is a layering violation. bio_set_ioprio is >>> the one which introduces the scheduler thing into the block layer, >>> this commit just wants to do a little improvement based on that. This >>> commit helps CFS task save some IO time when preempted by RT heavily. >> >> Listen, both this and the previous content ioprio thing show a glaring >> misunderstanding of how to design these kinds of things. You have no >> grasp of what the different layers do, or how they interact. I'm not >> sure how to put this kindly, but it's really an awful idea to hardcore >> some CFS helper into the IO scheduler. The fact that you had to fiddle >> around with headers to make it work was the first warning sign, and the >> fact that you didn't stop at that point to consider how it could be >> properly done makes it even worse. >> >> You need to stop sending kernel patches until you understand basic >> software design. Neither of these patches are going anywhere until this >> happens. There's been plenty of feedback to telling you that, but you >> seem to just ignore it and plow on ahead. Stop. > Ok, thanks for pointing this out, I will follow your advice. But I > have to say that '[PATCHv9 1/1] block: introduce content activity > based ioprio' really solved layering violation things. I would like to > humbly ask for your kindly patient to have a look, as it is really > helpful. If properly designed, that patch would *not* be a block layer API/function and so does not need review by block layer folks/Jens as it would simply set an IO prio for a BIO issued by an FS. So that patch needs to be accepted by FS people, for the FS you are interested in. -- Damien Le Moal Western Digital Research