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Mon, 29 Jul 2024 04:50:46 +0000 (GMT) Message-ID: <14377a5b-c83d-405a-bcec-6932dfdc99b9@linux.ibm.com> Date: Mon, 29 Jul 2024 10:20:45 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 0/1] Add visibility for native NVMe miltipath using debugfs To: Sagi Grimberg , linux-nvme@lists.infradead.org Cc: hch@lst.de, kbusch@kernel.org, axboe@fb.com, gjoyce@linux.ibm.com References: <20240722093124.42581-1-nilay@linux.ibm.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: tlXuO0l5kwagbRR14sxdW_-IsI8iTCTm X-Proofpoint-GUID: tlXuO0l5kwagbRR14sxdW_-IsI8iTCTm X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.28.16 definitions=2024-07-29_02,2024-07-26_01,2024-05-17_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 adultscore=0 lowpriorityscore=0 mlxscore=0 bulkscore=0 malwarescore=0 priorityscore=1501 impostorscore=0 clxscore=1015 mlxlogscore=999 suspectscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2407110000 definitions=main-2407290025 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240728_215105_107963_B17104F0 X-CRM114-Status: GOOD ( 15.19 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 7/29/24 02:17, Sagi Grimberg wrote: > >> # cat /sys/kernel/debug/block/nvme2n2/multipath >> io-policy: numa >> io-path: >> -------- >> node  current-path  ctrl    ana-state >> 2     nvme2c2n2     nvme2   optimized >> 3     nvme2c0n2     nvme0   optimized >> >> The above output shows that current selected iopolicy is numa. And when we >> have workload running I/O on numa node 2, accessing namespace "nvme2n2", >> it uses path nvme2c2n2 and controller nvme2 for forwarding data. Moreover >> the current ana-state for this path is optimized. Similarly, for I/O >> workload running on numa node 3 would use path nvme2c0n2 and controller >> nvme0. >> >> Now changing the iopolicy to round-robin, >> >> # echo "round-robin" > /sys/class/nvme-subsystem/nvme-subsys2/iopolicy >> >> # cat /sys/kernel/debug/block/nvme2n2/multipath >> io-policy: round-robin >> io-path: >> -------- >> node  rr-path       ctrl    ana-state >> 2     nvme2c2n2     nvme2   optimized >> 2     nvme2c0n2     nvme0   optimized >> 3     nvme2c2n2     nvme2   optimized >> 3     nvme2c0n2     nvme0   optimized > > Can we avoid a formatted output in sysfs? I'd much rather prefer that nvme-cli/libnvme to > format this (maybe this may be wanted as json in the future for example)... > > Can we simply expose the individual components and have userpace format the output? Yes that's what I am planning to implement. The sysfs would only expose the relevant information from NVMe driver and then libnvme/nvme-cli format the sysfs output as needed. Thanks, --Nilay