Re: Memory mapped files question

Chris Friesen (cfriesen@nortelnetworks.com)
Mon, 14 Apr 2003 16:39:42 -0400

H. Peter Anvin wrote:
> Followup to: <11640000.1050332688@[10.10.2.4]> By author: "Martin J.
> Bligh" <mbligh@aracnet.com> In newsgroup: linux.dev.kernel
>
>>> Martin, something which was not mentioned last week (I've just checked).
>>>
>>> It's OK if we never write to disk unless explicitely told, but will we
>>> writeback when we munmap?

> munmap() and fsync() or msync() will flush it to disk; there is no reason
> munmap() should unless perhaps the file was opened O_SYNC.

Wait a minute. Shouldn't a file opened O_SYNC flush the writes as they happen,
removing the requirement for any explicit syncing? If it doesn't there are some
very broken apps around.

Chris

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