As far as we know, fadvise(DONTNEED) does not support metadata cache cleaning. We think that is desirable under massive small files situations. Another thing is that do people accept the behavior of feeding a directory fd to fadvise will recusively clean all page caches of files inside that directory?
On 2013/12/17 1:45, Cong Wang wrote:
On Mon, Dec 16, 2013 at 7:00 AM, Li Wang <[email protected]> wrote:This patch extend the 'drop_caches' interface to support directory level cache cleaning and has a complete backward compatibility. '{1,2,3}' keeps the same semantics as before. Besides, "{1,2,3}:DIRECTORY_PATH_NAME" is allowed to recursively clean the caches under DIRECTORY_PATH_NAME. For example, 'echo 1:/home/foo/jpg > /proc/sys/vm/drop_caches' will clean the page caches of the files inside 'home/foo/jpg'.This interface is ugly... And we already have a file-level drop cache, that is, fadvise(DONTNEED). Can you extend it if it can't handle a directory fd?
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