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Wed, 15 Oct 2025 06:19:58 +0000 (GMT) Message-ID: <4faf672b-ad74-41dc-9518-bbb9af557544@linux.ibm.com> Date: Wed, 15 Oct 2025 11:49:57 +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: Hannes Reinecke , linux-nvme@lists.infradead.org Cc: kbusch@kernel.org, hch@lst.de, axboe@kernel.dk, dwagner@suse.de, 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> Content-Language: en-US From: Nilay Shroff In-Reply-To: <359e3d8f-4db7-4430-8520-4fed9de4f48e@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 3t2Z5JI8UIfk-WFQ-GZORG1XbvYxQDzn X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDExMDAxMSBTYWx0ZWRfX6D75ZoaSUUB+ juUn3ik2NsNX1V0mq2SGG7yyZaXOu68dGjJVdz7RP0WrqyDi+/WG1RVan/uIKbSwcSqDuCIZZv4 bpYb3glgVFja/UbGIpwpoAoAniFF7cIxfzh9AX/KM0d52Pvxcp14R4dSCwcK/yorLuVpQvdKOrh Yo7Rd4M+PZKPfx7fTbOX/XTr6F4EHORAKbl0s33pYERVwWVIpgJ76mHEdMlHS///NFjsMF3MEmv kDBb2j83z/lRqBBLDly56c9960PoXBQrjmkm/VuHd1qPl3aJSg5FTjPjMZbYILt1SMi53C5GGab qXXy8EVT/36rqGjvNIultefa26ajOYf7+JMdzsY6Ov4NZ92WAu9sdknu2BvhG+JRmy/wIzluKR+ 6Ed3vcTr65ShWu2DauUAnyZns9xwzw== X-Proofpoint-GUID: 3t2Z5JI8UIfk-WFQ-GZORG1XbvYxQDzn X-Authority-Analysis: v=2.4 cv=QZ5rf8bv c=1 sm=1 tr=0 ts=68ef3d13 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=x6icFKpwvdMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=O1fYyZKE8seMAvTDqbsA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=cPQSjfK2_nFv0Q5t_7PE:22 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=2025-10-15_02,2025-10-13_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 bulkscore=0 suspectscore=0 spamscore=0 malwarescore=0 impostorscore=0 clxscore=1015 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510020000 definitions=main-2510110011 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251014_232007_749715_E40A37B6 X-CRM114-Status: GOOD ( 13.03 ) 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 10/13/25 12:03 PM, Hannes Reinecke wrote: > On 10/9/25 12:05, Nilay Shroff wrote: >> This commit introduces a new debugfs attribute, "adaptive_stat", under >> both per-path and head debugfs directories (defined under /sys/kernel/ >> debug/block/). This attribute provides visibility into the internal >> state of the adaptive I/O policy to aid in debugging and performance >> analysis. >> >> For per-path entries, "adaptive_stat" reports the corresponding path >> statistics such as I/O weight, selection count, processed samples, and >> ignored samples. >> >> For head entries, it reports per-CPU statistics for each reachable path, >> including I/O weight, path score, smoothed (EWMA) latency, selection >> count, processed samples, and ignored samples. >> >> These additions enhance observability of the adaptive I/O path selection >> behavior and help diagnose imbalance or instability in multipath >> performance. >> >> Signed-off-by: Nilay Shroff >> --- >>   drivers/nvme/host/core.c      |   3 + >>   drivers/nvme/host/debugfs.c   | 117 ++++++++++++++++++++++++++++++++++ >>   drivers/nvme/host/multipath.c |   2 + >>   3 files changed, 122 insertions(+) >> > Reviewed-by: Hannes Reinecke > > Might be an idea to have support for queue-depth in here, too. > Currently queue_depth and numa_nodes attributes are created under sysfs, so do you meant to move those attributes from sysfs to debugfs? Thanks, --Nilay