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Lazy-Writer Thread (Windows CE 5.0)

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Each cache has its own lazy-writer thread that searches for and commits dirty sectors. By default, the priority of this thread is set at idle, however, you can override this priority for a profile using the following registry setting:

[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\<Profile Name>\FATFS]
    "LazyWriterThreadPrio256"=dword:xx

The lazy-writer thread uses the following algorithm.

if (event set indicating that there are dirty sectors to commit) {
    while (TRUE){
        Enter main critical section protecting the cache from main threads;
        if (no more dirty sectors) {
            Leave main critical section;
            break;
        }
        Find first dirty run of sectors to commit;
        Commit those dirty sectors;
        Leave main critical section;
    }
}
Reset event indicating there are no dirty sectors to commit.

A main thread will not be able to interrupt the lazy-writer thread while it is committing dirty sectors. However, since the lazy-writer thread always leaves the main critical section, a main thread will have priority in fulfilling its requests. The dirty sectors check occurs while the lazy-writer thread holds the critical section to prevent race conditions. It then checks the dirty sector count and resets the event.

See Also

Cache Manager

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