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Thu, 16 Oct 2025 11:04:04 +0000 (GMT) Message-ID: Date: Thu, 16 Oct 2025 16:34:03 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCHv2 4/4] nvme-multipath: add debugfs attribute for adaptive I/O policy stat To: Daniel Wagner , Hannes Reinecke Cc: linux-nvme@lists.infradead.org, kbusch@kernel.org, hch@lst.de, axboe@kernel.dk, gjoyce@ibm.com References: <20251009100608.1699550-1-nilay@linux.ibm.com> <20251009100608.1699550-5-nilay@linux.ibm.com> <359e3d8f-4db7-4430-8520-4fed9de4f48e@suse.de> <4faf672b-ad74-41dc-9518-bbb9af557544@linux.ibm.com> <803f429d-60f3-4af7-9535-37a2038e53c1@flourine.local> Content-Language: en-US From: Nilay Shroff In-Reply-To: <803f429d-60f3-4af7-9535-37a2038e53c1@flourine.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=M5ZA6iws c=1 sm=1 tr=0 ts=68f0d128 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=x6icFKpwvdMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=h6zKowGUZeksCTtIWkMA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=cPQSjfK2_nFv0Q5t_7PE:22 X-Proofpoint-GUID: 7RhhJ-j-SNQSB1R-Ssb4R0tp8hr5veF1 X-Proofpoint-ORIG-GUID: 7RhhJ-j-SNQSB1R-Ssb4R0tp8hr5veF1 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDEwMDE0MCBTYWx0ZWRfX7hyHf1fKoWls 0uJqTWfk9vTTjMeuofsTj540y73EQ8B/UvGmlaigLifxfoanQxPnEL9tbLQk8R46cO5MSP50dcX KgTuOkV/a+vHhlhKCaMoSC1oWLlWRTwTG5mgefqZicsikW2xgZfM0GuGfFKh86z85rMRBID/BqC 38aCe0QW6JZpf9tJrxD3S2Z0n0kN0T+q30SS8ZoDVehrwt/XqMQufpRazrChM3wqXekTl0IADw9 8dhfkKi4r01Pd6pkrvegaktzEFySGiHQnRF6GdXq2ul8pQBuOZ9/V6Gwiu8psdox2JrCoyZEo6v MPAlP0jeF3u0NI7Nbn7QCizSz7q6kRpC6YKm6uE3/me1/TtIBm9sUja8GiB2qUM5/Jsf5a/Iugx OWuZo9+sMQbSvBrcwmuYNh1RBtkbtg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-10-16_01,2025-10-13_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 bulkscore=0 spamscore=0 clxscore=1015 impostorscore=0 phishscore=0 adultscore=0 suspectscore=0 priorityscore=1501 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510020000 definitions=main-2510100140 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251016_040414_049619_66641D95 X-CRM114-Status: GOOD ( 15.58 ) 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 10/16/25 1:57 PM, Daniel Wagner wrote: > On Thu, Oct 16, 2025 at 08:14:19AM +0200, Hannes Reinecke wrote: >>> Currently queue_depth and numa_nodes attributes are created under >>> sysfs, so do you meant to move those attributes from sysfs to >>> debugfs? >>> >> Yes. sysfs information can be perused by udev rules, and that assumes >> the information in there will not change without a 'CHANGE' uevent. >> So it's questionable whether volatile information like the queue depth >> or the round-robin path selection should be presented there. >> I'd rather have it moved into debugfs. >> >> But that might be personal preference. > > If this moves to debugfs, I think nvme-cli should not show it per > default. Don't want to get lots of questions why the value is not > showed or updated. That’s a fair concern — debugfs isn’t guaranteed to be available in production systems (it may be disabled or not mounted), so depending on it from nvme-cli would be unreliable. Given that, I think it’s safer to keep queue_depth and numa_node in sysfs for now since they’re already part of the sysfs and used by nvme-cli. Thanks, --Nilay