Messages in this thread | | | Date | Fri, 10 Feb 2006 16:29:21 +1100 | From | Nick Piggin <> | Subject | Re: msync() behaviour broken for MS_ASYNC, revert patch? |
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Andrew Morton wrote: > Nick Piggin <nickpiggin@yahoo.com.au> wrote: > >>If you want to start the IO *now* without waiting on it, call msync(MS_ASYNC) >> If you don't want to start the IO now, that's really easy, do nothing. >> If you want to start the IO now and also wait for it to finish, call msync(MS_SYNC) > > > I've already explained the problems with the start-io-in-MS_ASYNC approach. >
But I've explained that they only matter for people using it in stupid ways. fsync also poses a performance problem for programs that call it after every write(2).
> >> Presently, the first option is unavailable. > > > We need to patch the kernel either way. There's no point in going back to > either the known-problematic approach or to something half-assed. >
The system call indicates to the kernel that IO submission should be started. The earlier the kernel does that, the better (because it is likely that an MS_SYNC is coming soon).
I think the current way of just moving the dirty bits is half-assed.
Is a more efficient implementation know-problematic? What applications did you observe problems with, can you remember? Because the current behaviour is also known-problematic for linux@horizon.com (who are you anyway?)
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