Re: [PATCH RFC v7 00/23] DEPT(Dependency Tracker)

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Jan 19, 2023 at 03:23:08PM +0900, Byungchul Park wrote:
> Boqun wrote:
> > *	Looks like the DEPT dependency graph doesn't handle the
> > 	fair/unfair readers as lockdep current does. Which bring the
> > 	next question.
> 
> No. DEPT works better for unfair read. It works based on wait/event. So
> read_lock() is considered a potential wait waiting on write_unlock()
> while write_lock() is considered a potential wait waiting on either
> write_unlock() or read_unlock(). DEPT is working perfect for it.
> 
> For fair read (maybe you meant queued read lock), I think the case
> should be handled in the same way as normal lock. I might get it wrong.
> Please let me know if I miss something.

>From the lockdep/DEPT point of view, the question is whether:

	read_lock(A)
	read_lock(A)

can deadlock if a writer comes in between the two acquisitions and
sleeps waiting on A to be released.  A fair lock will block new
readers when a writer is waiting, while an unfair lock will allow
new readers even while a writer is waiting.




[Index of Archives]     [Linux RAID]     [Linux SCSI]     [Linux ATA RAID]     [IDE]     [Linux Wireless]     [Linux Kernel]     [ATH6KL]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Device Mapper]

  Powered by Linux