在取每个rq前,会判断low-level drive是否busy(不能再处理更多的请求了),如果busy那么scsi_request_fn退出循环。这个过程见图中1如果request_queue为空,并且low-leveldirve可以继续处理请求,那么会找到当前request_queue对应的cfq_data,这个结构中维护了一些rbtree,从而可以找到下一次待处
关于list中的WRITE_ONCE使用,over stackflow上也有讨论:WRITE_ONCE in linux kernel lists 对此我的理解是:list模块是无锁化设计(不是说不需要锁,而是API里不使用锁,需要调用者根据实际情况加锁),且API都是内联函数,对 head->next 使用WRITE_ONCE,主要是为了保证原子化操作(这是volatile的又一特性,避免超16位...
Thedmesg commandin Linux allows viewing kernel ring buffer messages, which are system logs related to hardware and kernel events. These logs are valuable for diagnosing hardware issues, driver problems, and system initialization processes. By runningdmesg, you can access these logs directly from the ...
使用Source Insight阅读Linux内核代码是很方便的,面对那么多的代码文件,也可以做到很快的响应。但同时也存在一些小的痛点,比如本文将要介绍的__read_mostly的误解析问题,就导致代码跟踪中断。 1. __read_mostly误解析 在跟踪数据帧接收流程的过程中,驱动接收完数据包之后,会调用netif_receive_skb把帧交给协议栈处理,...
Downgrading to kernels prior tokernel-4.18.0-240.el8causes performance to resume to previous levels. Resolution Red Hat Enterprise Linux 8 Update packagenfs-utilsto2.3.3-57.el8(released withRHBA-2022:7768) or later, which introduces thenfsraheadtool, which you can use it to modify thereadahead...
The Linux kernel in this repository is the Linux kernel from Xilinx together with drivers & patches applied from Analog Devices. Details about the drivers that are of interest [and supported] by this repository can be found on the Analog Devices wiki. This readme focuses on details specific to...
Having worked pretty much exclusively in a Unix world for the past two decades, my experience with Windows development is rather limited and I'd expect there to definitely be bugs and rough edges in the Windows code. The Windows version of the DwarFS filesystem driver relies on the awesome ...
[ 2623.420296] CPU: 0 PID: 2057 Comm: mount Kdump: loaded Not tainted 3.10.0-1160.el7.x86_64 #1 [ 2623.420931] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 [ 2623.421391] Call Trace: [ 2623.421638] [<ffffffff88181340>] dump_stack+0x19/0x1b [ 2623.421995] [<ffffffff87a9b...
Description of problem: === Linux kernel untar failed with "xz: (stdin): Read error: Invalid argument" immediate after add-brick linux-4.4.36/arch/arm/boot/dts/imx28-cfa10058.dts linux-4.4.36/arch/arm/boot/dts/imx28-duckbill.dts xz: (stdin): Read error: Invalid argument linux-4.4.3...
- I tried read UVC header via v4l2(https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/pixfmt-meta-uvc.html) - The procedure is something like that in librealsense(https://github.com/IntelRealSense/librealsense/blob/master/src/linux/backend-v4l2.h). Open the video captu...