Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S965090AbcJXN3E (ORCPT <rfc822;w@1wt.eu>);
        Mon, 24 Oct 2016 09:29:04 -0400
Received: from mail-yb0-f179.google.com ([209.85.213.179]:34098 "EHLO
        mail-yb0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S964885AbcJXN24 (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 24 Oct 2016 09:28:56 -0400
From: Kashyap Desai <kashyap.desai@broadcom.com>
References: <97184c74229af78b0d97e6b8016af972@mail.gmail.com> <20161021213121.GA10030@vader.DHCP.thefacebook.com>
In-Reply-To: <20161021213121.GA10030@vader.DHCP.thefacebook.com>
MIME-Version: 1.0
X-Mailer: Microsoft Outlook 14.0
Thread-Index: AQJ1Bhg6X1XmO0v7tbYDuu2SASwMzQINeIO9n2F1uLA=
Date: Mon, 24 Oct 2016 18:35:01 +0530
Message-ID: <1f7cec69e6e12b6baa8e7f180a8e41b3@mail.gmail.com>
Subject: RE: Device or HBA level QD throttling creates randomness in sequetial workload
To: Omar Sandoval <osandov@osandov.com>
Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-block@vger.kernel.org, axboe@kernel.dk,
        Christoph Hellwig <hch@infradead.org>, paolo.valente@linaro.org
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 909
Lines: 30

>
> On Fri, Oct 21, 2016 at 05:43:35PM +0530, Kashyap Desai wrote:
> > Hi -
> >
> > I found below conversation and it is on the same line as I wanted some
> > input from mailing list.
> >
> > http://marc.info/?l=linux-kernel&m=147569860526197&w=2
> >
> > I can do testing on any WIP item as Omar mentioned in above
discussion.
> > https://github.com/osandov/linux/tree/blk-mq-iosched

I tried build kernel using this repo, but looks like it is not allowed to
reboot due to some changes in <block> layer.

>
> Are you using blk-mq for this disk? If not, then the work there won't
affect you.

YES. I am using blk-mq for my test. I also confirm if use_blk_mq is
disable, Sequential work load issue is not seen and <cfq> scheduling works
well.

>
> > Is there any workaround/alternative in latest upstream kernel, if user
> > wants to see limited penalty  for Sequential Work load on HDD ?
> >
> > ` Kashyap
> >