Messages in this thread | | | Date | Thu, 9 Feb 2006 19:50:35 -0800 | From | Andrew Morton <> | Subject | Re: msync() behaviour broken for MS_ASYNC, revert patch? |
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Nick Piggin <nickpiggin@yahoo.com.au> wrote: > > > It's a bit of a disaster if you happen to msync(MS_ASYNC) the same page at > > any sort of frequency - we have to wait for the previous I/O to complete > > before new I/O can be started. That was the main problem which caused this > > change to be made. You can see that it'd make 100x or 1000x speed improvements > > with some sane access patterns. > > > > I'm not sure you'd have to do that, would you? Just move the dirty bit > from the pte and skip the page if it is found locked or writeback.
That would make MS_ASYNC mean "start I/O now, unless there's I/O in progress, in whch case start I/O in 30 seconds. That's not good.
If we're going to change the kernel, better off using fadvise() enhancements, whic are also useful for post-write() operations.
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