d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Giant is special. How do I love thee? Let me count the ways?

Browse Source 
errr, I mean "Enumerate how the giant lock differs from other locks"

Please let me know if I missed any.  Or misrepresented any...

Reviewed by: ssouhlal@
This commit is contained in:
imp 2007-05-31 00:05:59 +00:00
parent 2d2fc4992a
commit 67962a47d6
1 changed files with 20 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
share/man/man9/locking.9
View File

@ -172,7 +172,26 @@ is atomically released before the thread is blocked, then reacquired
before the function call returns.
.Ss Giant
Giant is a special instance of a sleep lock.
it has several special characteristics.
It has several special characteristics.
.Bl -enum
.It
It is recursive.
.It
Drivers can request that Giant be locked around them, but this is
going away.
.It
You can sleep while it has recursed, but other recursive locks cannot.
.It
Giant must be locked first.
.It
There are places in the kernel that drop Giant and pick it back up
again.
Sleep locks will do this before sleeping.
Parts of the Network or VM code may do this as well, depending on the
setting of a sysctl.
This means that you cannot count on Giant keeping other code from
running if your code sleeps, even if you want it to.
.El
.Ss Sleep/wakeup
The functions
.Fn tsleep ,