Messages in this thread | | | Date | Wed, 29 Dec 2010 23:03:14 +0800 | Subject | Re: [PATCH v0] add nano semaphore in kernel | From | Hillf Danton <> |
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On Wed, Dec 29, 2010 at 10:58 PM, Daniel Walker <dwalker@codeaurora.org> wrote: > On Wed, 2010-12-29 at 22:42 +0800, Hillf Danton wrote: >> On Wed, Dec 29, 2010 at 7:47 PM, Arnd Bergmann <arnd@arndb.de> wrote: >> > On Tuesday 28 December 2010 16:51:30 Daniel Walker wrote: >> >> We for sure don't want new semaphores, or new semaphore usage in the >> >> kernel .. >> >> Would you please, Daniel, explain why there are so my file systems under >> the fs directory? Would you think the ext file system is better than others? >> >> And why there are in kernel spin lock, read/write lock, mutex, rw_mutex, >> rtmutx, and semaphore, timer and hrtimer? >> >> Could timer be removed tonight? > > The problem with semaphores is that people use them in ways that are not > very nice, and not very efficient.. Since they are so flexible they can > be used in all sorts of ways, many of which are not clean. This is why, > if you read the kernel history, most semaphore have been removed from > the kernel and replaced with much nicer and cleaner mutexes. > > Daniel
Thanks for sharing the knowledge about rtmutx and semaphore. Hillf
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