sysfs block
/sys/block/*
首先，在 genhd.c 中:
static DEVICE_ATTR(range, 0444, disk_range_show, NULL);
static DEVICE_ATTR(ext_range, 0444, disk_ext_range_show, NULL);
static DEVICE_ATTR(removable, 0444, disk_removable_show, NULL);
static DEVICE_ATTR(hidden, 0444, disk_hidden_show, NULL);
static DEVICE_ATTR(ro, 0444, disk_ro_show, NULL);
static DEVICE_ATTR(size, 0444, part_size_show, NULL);
static DEVICE_ATTR(alignment_offset, 0444, disk_alignment_offset_show, NULL);
static DEVICE_ATTR(discard_alignment, 0444, disk_discard_alignment_show, NULL);
static DEVICE_ATTR(capability, 0444, disk_capability_show, NULL);
static DEVICE_ATTR(stat, 0444, part_stat_show, NULL);
static DEVICE_ATTR(inflight, 0444, part_inflight_show, NULL);
static DEVICE_ATTR(badblocks, 0644, disk_badblocks_show, disk_badblocks_store);
static DEVICE_ATTR(diskseq, 0444, diskseq_show, NULL);
stat
实现 genhd.c 中的 part_stat_show
Documentation/block/stat.rst
in_flight
=========
This value counts the number of I/O requests that have been issued to
the device driver but have not yet completed. It does not include I/O
requests that are in the queue but not yet issued to the device driver.
inflight = part_in_flight(bdev);
inflight
和 /sys/block/*/stat 中的 in_flight 的关系
- part_inflight_show 会分别展示 read 和 write ，而 /sys/block/*/stat 中的 in_flight 中两个结果是合并的
- part_inflight_show 是考虑 mq 的，也是对于 nvme ，/sys/block/*/stat 中的 in_flight 的输出是 0
在看看啥意思，当时写的，忘记了
part_inflight_show 中分别统计了 mq 和非 mq 的情况， part_in_flight_rw 说明， 是将统计数据放到 block_device::bd_stats::in_flight 中的
而 mq 的设备:
- bio_start_io_acct
bio_end_io_acct
/sys/block/*/device
scsi
scsi 的: drivers/scsi/scsi_sysfs.c
scsi_sdev_attrs
➜ device ls /sys/block/sda/device
blacklist delete evt_capacity_change_reported evt_soft_threshold_reached ioerr_cnt power scsi_device subsystem vpd_pg0 wwid
block device_blocked evt_inquiry_change_reported generic iorequest_cnt queue_depth scsi_disk timeout vpd_pg83
bsg device_busy evt_lun_change_reported inquiry iotmo_cnt queue_type scsi_generic type vpd_pgb0
cdl_enable driver evt_media_change iocounterbits modalias rescan scsi_level uevent vpd_pgb1
cdl_supported eh_timeout evt_mode_parameter_change_reported iodone_cnt model rev state vendor vpd_pgb2
echo offline > /sys/block/sdx/device/state
nvme
drivers/nvme/host/sysfs.c
➜ device ls /sys/block/nvme0n1/device
address cntrltype dev firmware_rev kato ng0n1 nvme0n1 queue_count reset_controller sqsize subsysnqn transport
cntlid dctype device hwmon0 model numa_node power rescan_controller serial state subsystem uevent
device -> ../../../0000:83:00.0
virtio-blk
➜ ~ ls /sys/block/vda/device
block device driver features modalias power status subsystem uevent vendor
device -> ../../../virtio1
/sys/block/*/trace/
用于 blktrace ，只有打开 CONFIG_BLK_DEV_IO_TRACE 这个目录才存在。
/sys/block/*/queue/
add_random discard_max_hw_bytes logical_block_size nr_requests virt_boundary_mask
atomic_write_boundary_bytes discard_zeroes_data max_discard_segments nr_zones write_cache
atomic_write_max_bytes dma_alignment max_hw_sectors_kb optimal_io_size write_same_max_bytes
atomic_write_unit_max_bytes fua max_integrity_segments physical_block_size write_zeroes_max_bytes
atomic_write_unit_min_bytes hw_sector_size max_sectors_kb read_ahead_kb zone_append_max_bytes
chunk_sectors io_poll max_segment_size rotational zone_write_granularity
dax io_poll_delay max_segments rq_affinity zoned
discard_granularity iostats minimum_io_size scheduler
discard_max_bytes iostats_passthrough nomerges stable_writes
block/blk-mq-sysfs.c
注意，以上内容分为两个部分，其中 request-based 多出来一些内容:
/* Common attributes for bio-based and request-based queues. */
static struct attribute *queue_attrs[] = { }
/* Request-based queue attributes that are not relevant for bio-based queues. */
static struct attribute *blk_mq_queue_attrs[] = {
/*
* Attributes which require some form of locking other than
* q->sysfs_lock.
*/
&elv_iosched_entry.attr,
&queue_requests_entry.attr,
#ifdef CONFIG_BLK_WBT
&queue_wb_lat_entry.attr,
#endif
/*
* Attributes which don't require locking.
*/
&queue_rq_affinity_entry.attr,
&queue_io_timeout_entry.attr,
NULL,
};
/sys/block/*/mq/
block/blk-sysfs.c
virtio-blk 在一个 4 core 的虚拟机上
├── 0
│ ├── cpu0
│ ├── cpu_list
│ ├── nr_reserved_tags
│ └── nr_tags (256)
├── 1
│ ├── cpu1
│ ├── cpu_list
│ ├── nr_reserved_tags
│ └── nr_tags
├── 2
│ ├── cpu2
│ ├── cpu_list
│ ├── nr_reserved_tags
│ └── nr_tags
└── 3
├── cpu3
├── cpu_list
├── nr_reserved_tags
└── nr_tags
实现的代码在 : block/blk-mq-sysfs.c
具体的路径 : /sys/block/nvme0n1/mq
因为创建的是 kobject_add 是自动添加的目录:
hctx_for_each_ctx(hctx, ctx, i) {
ret = kobject_add(&ctx->kobj, &hctx->kobj, "cpu%u", ctx->cpu);
if (ret)
goto out;
}
这里的内容相对于 debugfs ，太弱了
/proc/partitions
这个接口本身很简单，但是我
/proc/diskstats
🧀 cat /proc/diskstats
259 0 nvme1n1 1141423 165624 55597064 204574 5461706 6557411 242187142 967652 0 1014962 1345517 0 0 0 0 872323 173291
259 1 nvme1n1p1 1140939 164658 55574251 204415 5461483 6541994 242062036 967375 0 1014812 1171790 0 0 0 0 0 0
259 2 nvme1n1p2 114 15 7096 48 221 15417 125104 276 0 200 325 0 0 0 0 0 0
259 3 nvme1n1p3 277 951 12045 102 2 0 2 0 0 92 102 0 0 0 0 0 0
259 4 nvme0n1 154 0 8144 10 0 0 0 0 0 15 10 0 0 0 0 0 0
259 5 nvme0n1p1 59 0 4432 4 0 0 0 0 0 6 4 0 0 0 0 0 0
8 16 sdb 94 0 4504 94 0 0 0 0 0 94 94 0 0 0 0 0 0
8 0 sda 94 0 4504 32 0 0 0 0 0 29 32 0 0 0 0 0 0
7 0 loop0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
7 1 loop1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
7 2 loop2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
7 3 loop3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
7 4 loop4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
7 5 loop5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
7 6 loop6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
7 7 loop7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
- Documentation/ABI/testing/procfs-diskstats
-
Documentation/admin-guide/iostats.rst
- https://bean-li.github.io/dive-into-iostat/
- https://ykrocku.github.io/blog/2014/04/11/diskstats/
实现的位置参考:
- blk_account_io_done
在 iostat -xz 5 中 w_await 是所有 io 的平均值。
这里 ifutil 的项目中，
/proc/diskstats 的具体每一项的实现在这里
- /sys/devices/pci0000:00/0000:00:08.0/nvme/nvme1/nvme1n1/stat
其他
源码
genhd.c
static int __init proc_genhd_init(void)
{
proc_create_seq("diskstats", 0, NULL, &diskstats_op);
proc_create_seq("partitions", 0, NULL, &partitions_op);
return 0;
}
对应的接口为:
- /sys/block/sda/ 下的各种
register_blkdev 的调用，只要内存存在这个模块，就会进行对应的注册。
两个 timeout 接口
/sys/block/sda/device/timeout /sys/block/sda/queue/io_timeout
static ssize_t queue_io_timeout_show(struct request_queue *q, char *page)
{
return sprintf(page, "%u\n", jiffies_to_msecs(q->rq_timeout));
}
/*
* TODO: can we make these symlinks to the block layer ones?
*/
static ssize_t
sdev_show_timeout (struct device *dev, struct device_attribute *attr, char *buf)
{
struct scsi_device *sdev;
sdev = to_scsi_device(dev);
return snprintf(buf, 20, "%d\n", sdev->request_queue->rq_timeout / HZ);
}
static ssize_t
sdev_store_timeout (struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct scsi_device *sdev;
int timeout;
sdev = to_scsi_device(dev);
sscanf (buf, "%d\n", &timeout);
blk_queue_rq_timeout(sdev->request_queue, timeout * HZ);
return count;
}
static DEVICE_ATTR(timeout, S_IRUGO | S_IWUSR, sdev_show_timeout, sdev_store_timeout);
block/blk-timeout.c 中
blk_mq_timeout_work
device 的路径解析
/sys/devices/pci0000:00/0000:00:0a.0/virtio5/host1/target1:0:0/1:0:0:0/timeout
- 0000:00:0a.0
➜ ~ lspci -s 0000:00:0a.0
00:0a.0 SCSI storage controller: Virtio: Virtio SCSI
- virtio5 : 0000:00:0a.0 是第五个 virtio 设备
- host1 : 指的是 host 为 1
- target1:0:0 : ?
- 1:0:0:0 : 就是 Host Channel Id Lun 编号
其下存在三个目录:
/sys/devices/pci0000:00/0000:00:17.0/ata8/host7/target7:0:0/7:0:0:0
- scsi_device : 从这里触发，最后指回来
- scsi_disk : 存储 drivers/scsi/sd.c 中暴露的内容，因为当前设备是 scsi sd ，所以存储到此处
- block : /sys/block 软链接直接指向这里
- bsg
🧀 pwd
/sys/devices/pci0000:00/0000:00:17.0/ata8/host7/target7:0:0/7:0:0:0/scsi_device/7:0:0:0
🧀 ls
Permissions Size User Date Modified Name
lrwxrwxrwx 0 root 18 Oct 11:06 device -> ../../../7:0:0:0 # scsi_device 最后会指回来
drwxr-xr-x - root 18 Oct 11:06 power
lrwxrwxrwx 0 root 16 Oct 21:42 subsystem -> ../../../../../../../../../class/scsi_device
.rw-r--r-- 4.1k root 18 Oct 11:06 uevent
通过软链接，将各种代码整体放到一起。
不过，代码实现上，这些都是如何构成的。
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