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Sat, 21 Mar 2026 15:28:54 +0000 (GMT) From: Nilay Shroff To: linux-nvme@lists.infradead.org Cc: dwagner@suse.de, hare@suse.com, kbusch@kernel.org, hch@lst.de, gjoyce@ibm.com, wenxiong@linux.ibm.com, Nilay Shroff Subject: [PATCH 6/9] libnvme: add support for per-path diagnostic counters Date: Sat, 21 Mar 2026 20:58:05 +0530 Message-ID: <20260321152823.3197870-7-nilay@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260321152823.3197870-1-nilay@linux.ibm.com> References: <20260321152823.3197870-1-nilay@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: GEJItSBgAr9SBRS4DZ4-g8wCfUGMSFXO X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzIxMDEyOSBTYWx0ZWRfX8Yn0NyBuUAg2 +uERIbQRAaqY57K2ifWYZg/lQp2HPlKtsBewsuhwQrMhiJeMqcleppGXM7xmEpQNA6k5Q0GzWdM rKU4nFAbZunPVKwlYNom+gYIA2K091XYTI58YwH3/E00I6mcKooz2cCbVkIM6ZKrt5SU/qEaM99 zSKvL4359wbyM2llCeahZbpLJM+AoE4dVk57YpdbxZTqSCqrBGYI8/tMclLkP9ZiaO1ObZsaT26 OueDdOcBvH4BX5fQBfxFCjjHG9kRHTymVWgdXys+c2HUj1zK51/d2EDCFm0P8CQ6Zc9z5RiTZpx Cprbqt9jdtsNpmm6zmrIkku42934msW17WV2xEjKFmDfDdDOvl0Eh+YsQTL2VE0fnA8EuGhtOF2 CckDEP0nftskqKEtzMM9p+Zz3AeTKNMi/LO3GGhnBE2cJrxAo4Fk4afXjnt9wmCFLIrgSA6HYNE qheu1h1jjDsqPUzp04Q== X-Authority-Analysis: v=2.4 cv=bLEb4f+Z c=1 sm=1 tr=0 ts=69beb93e cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=NKCsueVTR_sD4m4h2I0A:9 X-Proofpoint-GUID: GEJItSBgAr9SBRS4DZ4-g8wCfUGMSFXO X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-21_05,2026-03-20_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 adultscore=0 clxscore=1015 phishscore=0 impostorscore=0 malwarescore=0 lowpriorityscore=0 suspectscore=0 bulkscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603210129 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260321_082905_048136_42A96DCC X-CRM114-Status: GOOD ( 15.57 ) 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 Add support for retrieving per-path diagnostic counters such as command_retry_count, command_error_count, and multipath_failover_count. These counters improve visibility into NVMe native multipath behavior and can be useful for tools such as nvme-top to display real-time statistics. Unlike other sysfs attributes, these counters can change dynamically. Annotate them with "!accessors:none" and provide custom implementations to always retrieve the latest (non-cached) values. Signed-off-by: Nilay Shroff --- libnvme/src/libnvme.ld | 3 +++ libnvme/src/nvme/private.h | 3 +++ libnvme/src/nvme/tree.c | 33 +++++++++++++++++++++++++++++++++ libnvme/src/nvme/tree.h | 27 +++++++++++++++++++++++++++ 4 files changed, 66 insertions(+) diff --git a/libnvme/src/libnvme.ld b/libnvme/src/libnvme.ld index c9550240d..20dcb24f1 100644 --- a/libnvme/src/libnvme.ld +++ b/libnvme/src/libnvme.ld @@ -167,6 +167,9 @@ LIBNVME_3 { nvme_path_get_write_sectors; nvme_path_reset_stat; nvme_path_update_stat; + nvme_path_get_command_retry_count; + nvme_path_get_command_error_count; + nvme_path_get_multipath_failover_count; nvme_filter_paths; nvme_read_config; nvme_read_key; diff --git a/libnvme/src/nvme/private.h b/libnvme/src/nvme/private.h index 858759a1b..bbddb9ba0 100644 --- a/libnvme/src/nvme/private.h +++ b/libnvme/src/nvme/private.h @@ -167,6 +167,9 @@ struct nvme_path { /*!generate-accessors*/ char *numa_nodes; //!accessors:none int grpid; int queue_depth; //!accessors:none + long multipath_failover_count; //!accessors:none + long command_retry_count; //!accessors:none + long command_error_count; //!accessors:none }; struct nvme_ns_head { diff --git a/libnvme/src/nvme/tree.c b/libnvme/src/nvme/tree.c index 3ad483557..a197b7a00 100644 --- a/libnvme/src/nvme/tree.c +++ b/libnvme/src/nvme/tree.c @@ -851,6 +851,39 @@ __public char *nvme_path_get_numa_nodes(nvme_path_t p) return p->numa_nodes; } +__public long nvme_path_get_multipath_failover_count(nvme_path_t p) +{ + _cleanup_free_ char *failover_count = NULL; + + failover_count = nvme_get_path_attr(p, "multipath_failover_count"); + if (failover_count) + sscanf(failover_count, "%ld", &p->multipath_failover_count); + + return p->multipath_failover_count; +} + +__public long nvme_path_get_command_retry_count(nvme_path_t p) +{ + _cleanup_free_ char *retry_count = NULL; + + retry_count = nvme_get_path_attr(p, "command_retry_count"); + if (retry_count) + sscanf(retry_count, "%ld", &p->command_retry_count); + + return p->command_retry_count; +} + +__public long nvme_path_get_command_error_count(nvme_path_t p) +{ + _cleanup_free_ char *error_count = NULL; + + error_count = nvme_get_path_attr(p, "command_error_count"); + if (error_count) + sscanf(error_count, "%ld", &p->command_error_count); + + return p->command_error_count; +} + static nvme_stat_t nvme_path_get_stat(nvme_path_t p, int curr) { if (curr < 0 || curr > 1) diff --git a/libnvme/src/nvme/tree.h b/libnvme/src/nvme/tree.h index c69d0c8a0..3c651743d 100644 --- a/libnvme/src/nvme/tree.h +++ b/libnvme/src/nvme/tree.h @@ -704,6 +704,33 @@ char *nvme_path_get_ana_state(nvme_path_t p); */ char *nvme_path_get_numa_nodes(nvme_path_t p); +/** + * nvme_path_get_multipath_failover_count() - Get multipath failover count + * @p: &nvme_path_t object + * + * Return: Number of times I/Os have to be failed over to another active path + * from path @p maybe due to any transient error observed on path @p + */ +long nvme_path_get_multipath_failover_count(nvme_path_t p); + +/** + * nvme_path_get_command_retry_count() - Get command retry count + * @p: &nvme_path_t object + * + * Return: Number of times any command issued to the namespace represented by + * path @p has to be retried + */ +long nvme_path_get_command_retry_count(nvme_path_t p); + +/** + * nvme_path_get_command_error_count() - Get command error count + * @p: &nvme_path_t object + * + * Return: Number of times command issued to the namespace represented by path + * @p returns non-zero status or error + */ +long nvme_path_get_command_error_count(nvme_path_t p); + /** * nvme_path_get_ctrl() - Parent controller of an nvme_path_t object * @p: &nvme_path_t object -- 2.53.0