lkml.org 
[lkml]   [2007]   [Feb]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH] update ctime and mtime for mmaped write
    From
    Date
    > > > This still does not address the situation where a file is 'permanently'
    > > > mmap'd, does it?
    > >
    > > So? If application doesn't do msync, then the file times won't be
    > > updated. That's allowed by the standard, and so portable applications
    > > will have to call msync.
    >
    > It is allowed, but it is clearly not useful behaviour. Nowhere is it set
    > in stone that we should be implementing just the minimum allowed.

    You're right. In theory, at least. But in practice I don't think
    this matters. Show me an application that writes to a shared mapping
    then doesn't call either msync or munmap and doesn't even exit.

    If there were lot of these apps, then this bug would have been fixed
    lots of years earlier. In fact there are _very_ few apps writing to
    shared mappings at all.

    Applications should be encouraged to call msync(MS_ASYNC) because:

    - it's very fast (basically a no-op) on recent linux kernels

    - it's the only portable way to guarantee, that the data you written
    will _ever_ hit the disk.

    There's really no downside to using msync(MS_ASYNC) in your
    application, so making an effort to support applications that don't do
    this is stupid, IMO.

    Thanks,
    Miklos
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-02-22 22:33    [W:0.019 / U:60.292 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site