Received-SPF: pass (google.com: domain of linux-kernel+bounces-134634-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Message-ID: <f5d57e3b-8168-41af-8e36-c7a21ef3a475@grimberg.me>
Date: Sun, 7 Apr 2024 23:08:23 +0300
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: WQ_UNBOUND workqueue warnings from multiple drivers
To: Kamaljit Singh <Kamaljit.Singh1@wdc.com>,
 Chaitanya Kulkarni <chaitanyak@nvidia.com>
Cc: "kbusch@kernel.org" <kbusch@kernel.org>,
 "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
 "linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>
References: <BYAPR04MB41513F04DB2ECDC3601CC36ABC2D2@BYAPR04MB4151.namprd04.prod.outlook.com>
 <c4057654-97bd-4721-9bed-9dd5ef8b3f8d@grimberg.me>
 <6d3af8dd-30c3-48d4-9083-7f00ea21ff8c@nvidia.com>
 <BYAPR04MB415196EC84756BA1876463DABC3E2@BYAPR04MB4151.namprd04.prod.outlook.com>
Content-Language: he-IL, en-US
From: Sagi Grimberg <sagi@grimberg.me>
In-Reply-To: <BYAPR04MB415196EC84756BA1876463DABC3E2@BYAPR04MB4151.namprd04.prod.outlook.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit


On 03/04/2024 2:50, Kamaljit Singh wrote:
> Sagi, Chaitanya,
>   
> Sorry for the delay, found your replies in the junk folder :(
>   
>>   Was the test you were running read-heavy?
> No, most of the failing fio tests were doing heavy writes. All were with 8 Controllers and 32 NS each. io-specs are below.
>
> [1] bs=16k, iodepth=16, rwmixread=0, numjobs=16
> Failed in ~1 min
>
> Some others were:
> [2] bs=8k, iodepth=16, rwmixread=5, numjobs=16
> [3] bs=8k, iodepth=16, rwmixread=50, numjobs=16

Interesting, that is the opposite of what I would suspect (I thought that
the workload would be read-only or read-mostly).

Does this happen with a 90-%100% read workload?

If we look at nvme_tcp_io_work() it is essentially looping
doing send() and recv() and every iteration checks if a 1ms
deadline elapsed. The fact that it happens on a 100% write
workload leads me to conclude that the only way this can
happen if sending a single 16K request to a controller on its
own takes more than 10ms, which is unexpected...

Question, are you working with a Linux controller? what
is the ctrl ioccsz?