• d0ca268 Initial commit of blktrace

Inital commit of blktrace userspace tools 包含下列几个文件：

    ├── blkparse.c
    ├── blktrace.c
    ├── blktrace.h
    ├── Makefile
    └── README

README

    % blktrace <dev>
    --- run task to generate load to be traced ---
    <SIGINT to kill>
    --- Generates:
        <dev>_dat.[0..ncpus] : Contains binary pdu data
        <dev>_out.[0..ncpus] : Contains binary trace …

• 2056a782f8e7 [PATCH] Block queue IO tracing support (blktrace) as of 2006-03-23
• v2.6.17-rc1 include/linux/blktrace_api.h
• v2.6.17-rc1 block/blktrace.c

blktrace.c 实现了 message 的填充（包括 message header 的构造 - struct blk_io_trace）并通过 relayfs 传递 message 到 userspace；blktrace_api 封装对 __blk_add_trace 的调用，Block IO layer 通过调用这些 APIs …

• include/linux/relay.h
• kernel/relay.c
• Documentation/filesystems/relay.txt

详细的 GUIDE 参考 Documentation/filesystems/relay.txt

A 'relay channel' is a kernel->user data relay mechanism implemented as a set of per-cpu kernel buffers ('channel buffers'), each represented as a regular file ('relay file') in user space. Kernel …

最近想在本子上装个 virtualbox 跑个 winxp，旧本子，一直用的 32 位 Debian，内核经常更新，现在版本是 5.0.0-rc2+

apt install virtualbox virtualbox-dkms 安装完后，建立虚拟机的时候报错，说不能加载 vboxdrv 模块

dkms build

想着可能是因为内核新，所以 dkms 工作没做好，干脆跑一下 dkms build。结果一跑，报错了：

    # dkms build -m virtualbox -v 5.2.24

    Kernel preparation unnecessary for this kernel.  Skipping...

    Building …

• fio HOWTO

I/O engine ioengine=str

Defines how the job issues I/O to the file. The following types are defined: ("libaio/sg/net/netsplice/rdma/rados/rbd/gfapi/gfapi_async" defines engine specific options)

    null
        Doesn't transfer any data, just pretends to. This is mainly used to
        exercise …

• fio HOWTO

Environment variables

Fio also supports environment variable expansion in job files. Any sub-string of the form ${VARNAME} as part of an option value (in other words, on the right of the '='), will be expanded to the value of the environment variable called VARNAME. If no such environment variable …

• fio HOWTO

fio accepts one or more job files describing what it is supposed to do.

The job file format is the classic ini file, where the names enclosed in [] brackets define the job name. You are free to use any ASCII name you want, except global which has special …

• fio HOWTO

How fio works

The first step in getting fio to simulate a desired I/O workload, is writing a job file describing that specific setup.

A job file may contain any number of threads and/or files -- the typical contents of the job file is a global section …

• F2FS: A New File System for Flash Storage
• F2FS: A New File System for Flash Storage.pdf
• F2FS: A New File System for Flash Storage, slides

By Jake Edge  May 4, 2016, LSFMM 2016

• Multipage bio_vecs
• block: prepare for multipage bvecs

In the block layer, larger I/O operations tend to be more efficient, but current kernels limit how large those operations can be. The bio_vec structure, which describes the buffer for an I/O operation …