Kernel

Historically, the only translation performed on I/O requests after they they left the file-system layer were logical sub disk implementation done in the device driver. No universal standard for how sub disks are configured and implemented exists, in fact pretty much every single platform and operating system have done it their own way. As FreeBSD migrates to other platforms it needs to understand these local conventions to be able to co-exist with other operating systems on the same disk.

Today folks at FreeBSDChina suggested me to have an interview with FreeBSD’s David XU (Yifeng XU), who is an active committer, and possibly the only src committer living in the mainland China.

Dillon wrote:

Well, this is fun. There are over 460 files in the 5.x source tree (360 in DFly) that make calls to malloc(… M_NOWAIT), and so far about 80% of the calls that I’ve reviewed generate inappropriate side effects when/if a failure occurs. CAM is the biggest violator… it even has a few panic() conditionals if a malloc(… M_NOWAIT) fails. Not Fun!

sys/vm/uma_int.h, rev 1.23是一个对于junsu几天前发现的问题的workaround。Alan说「Thanks. I’ve committed a change making a slightly larger increase to UMA_BOOT_PAGES.」

junsu昨天给了我一个perforce的URL: http://perforce.freebsd.org/chv.cgi?CH=45432

tjr写道: “Initial work on a new filesystem. Right now we can mount it, list
directories, and copy small files off it, but there is no write
support yet. This is going to be a simple extent-based filesystem,
borrowing ideas from NTFS and EFS.”

那么什么是extent呢？