From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from va-2-27.ptr.blmpb.com (va-2-27.ptr.blmpb.com [209.127.231.27]) (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 C1EF03DA7EE for ; Fri, 10 Apr 2026 16:21:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.127.231.27 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775838077; cv=none; b=cdJ2WKeM/eKop71oVycDU3M0fZG2sqrb0libH3MAPdXkh01A6/WSuN8hfXA7qyoQioK0mAYx7DnpITddjOgGL5FA+XBbXCLyskFfjysYt4sesknYVpR1eIPEiBVYhGQxmXa+L2q8jxbcmUef4IUu+Rcc5gQTgfRMeiAo+H/ql78= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775838077; c=relaxed/simple; bh=y1PdJ3gWJ5R1GIvBcyik80+KAxlRvCHGs6DcTjOjf3o=; h=Subject:Content-Type:Cc:From:Message-Id:Mime-Version:To: In-Reply-To:References:Date; b=hDcXAcmASKlQTwZTrU4VjQ+JlGjd0KatKNtRdowSWA/VKns+v60uvd8jgwf4Zw2LZ6qz/i4X9vEdP3zDhG7HphTKdAtZPhaPn/WamhusLCaIJprk7hN1NFEyyYcjgBZkdZU2ImIYBNvvY+xYnWZ9em4hGod8xdVhrYYRSG1aznw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fnnas.com; spf=pass smtp.mailfrom=fnnas.com; dkim=pass (2048-bit key) header.d=fnnas-com.20200927.dkim.feishu.cn header.i=@fnnas-com.20200927.dkim.feishu.cn header.b=tfgfdTqf; arc=none smtp.client-ip=209.127.231.27 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fnnas.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=fnnas.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=fnnas-com.20200927.dkim.feishu.cn header.i=@fnnas-com.20200927.dkim.feishu.cn header.b="tfgfdTqf" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; s=s1; d=fnnas-com.20200927.dkim.feishu.cn; t=1775838068; h=from:subject:mime-version:from:date:message-id:subject:to:cc: reply-to:content-type:mime-version:in-reply-to:message-id; bh=y1PdJ3gWJ5R1GIvBcyik80+KAxlRvCHGs6DcTjOjf3o=; b=tfgfdTqfOMoxP49NXPmpcTA2JBHsktTelBcyEvVqk+BeoSvWE7A9/VUhn5b5ybjvdJ1r2X qjxfghrot3l7GvQZ/a0QJ8u/FXrHEhNpXqdeiqvlGlJLLcrBnLIKNEw5FkY0Wg0RQpmylw EAJtnxRKCapp8QvYbacn5HhSZ7KJCOs5dMU/ZAONErQ/UXRvx5riYevWQwAibuVy2ncW3f ipwFMDLpC0o2/S9/+z1eQzqL6wgrtUCzDq1h7XWXqCLPs7oFnequn3z10Fe1mBkjZTlTGq iES+xi914ojktvOcC4UDoOS9jJqg2PIeman7hOv8AB8xzh3wyoUeJ4dpQ95L8A== Subject: Re: REGRESSION BISECTED: mq-deadline: covert to use request_queue->async_depth User-Agent: Mozilla Thunderbird X-Original-From: Yu Kuai Content-Type: text/plain; charset=UTF-8 Cc: "'Nilay Shroff'" , "'Bart Van Assche'" , "'Jens Axboe'" , , From: "Yu Kuai" Message-Id: <6e336fc5-bf39-41eb-a499-6728969bf164@fnnas.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Lms-Return-Path: Content-Language: en-US Reply-To: yukuai@fnnas.com To: "Doug Smythies" In-Reply-To: <004b01dcc8a9$7d6ac610$78405230$@telus.net> References: <005201dcc7ae$54a33010$fde99030$@telus.net> <9c1424f1-5d81-4308-bc93-0bdcde788501@fnnas.com> <004b01dcc8a9$7d6ac610$78405230$@telus.net> Content-Transfer-Encoding: quoted-printable Date: Sat, 11 Apr 2026 00:21:04 +0800 Received: from [192.168.1.104] ([39.182.0.184]) by smtp.feishu.cn with ESMTPS; Sat, 11 Apr 2026 00:21:06 +0800 Hi, =E5=9C=A8 2026/4/10 13:18, Doug Smythies =E5=86=99=E9=81=93: >> Do you ever use the async_depth for mq-deadline? > No. Then the only difference is the tag wake batch is changed from 1 to 8. Howe= ver, batch wake up is the base design of sbitmap. And I do admit tail latency is bad under high concurrency is probably due to wake up is unfair, this is a know sbitmap design flaw and not fixed yet. You could try change wake up batch back to 1. However, I don't think this i= s a good solution. And I'll suggest you to try increase nr_requests to see if t= ail latency gets better. Per --=20 Thansk, Kuai