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([2620:10d:c090:180::1:2c26]) by smtp.gmail.com with ESMTPSA id u69sm10113899pfj.116.2018.11.13.16.51.09 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 13 Nov 2018 16:51:10 -0800 (PST) Subject: Re: [PATCH] nvme: utilize two queue maps, one for reads and one for writes To: Guenter Roeck Cc: Keith Busch , Sagi Grimberg , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org References: <20181114004148.GA29545@roeck-us.net> From: Jens Axboe Message-ID: Date: Tue, 13 Nov 2018 17:51:08 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181114004148.GA29545@roeck-us.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/13/18 5:41 PM, Guenter Roeck wrote: > Hi, > > On Wed, Oct 31, 2018 at 08:36:31AM -0600, Jens Axboe wrote: >> NVMe does round-robin between queues by default, which means that >> sharing a queue map for both reads and writes can be problematic >> in terms of read servicing. It's much easier to flood the queue >> with writes and reduce the read servicing. >> >> Implement two queue maps, one for reads and one for writes. The >> write queue count is configurable through the 'write_queues' >> parameter. >> >> By default, we retain the previous behavior of having a single >> queue set, shared between reads and writes. Setting 'write_queues' >> to a non-zero value will create two queue sets, one for reads and >> one for writes, the latter using the configurable number of >> queues (hardware queue counts permitting). >> >> Reviewed-by: Hannes Reinecke >> Reviewed-by: Keith Busch >> Signed-off-by: Jens Axboe > > This patch causes hangs when running recent versions of > -next with several architectures; see the -next column at > kerneltests.org/builders for details. Bisect log below; this > was run with qemu on alpha. Reverting this patch as well as > "nvme: add separate poll queue map" fixes the problem. I don't see anything related to what hung, the trace, and so on. Can you clue me in? Where are the test results with dmesg? How to reproduce? -- Jens Axboe