i.e. multiple io-worker threads carrying out IO write fops are blocked in posix_writev to execute final write fop pwrite/pwritev in __posix_writev function ONE AFTER ANOTHER.
For example:
thread1: iot_worker -> ... -> posix_writev() |
thread2: iot_worker -> ... -> posix_writev() |
thread3: iot_worker -> ... -> posix_writev() -> __posix_writev()
thread4: iot_worker -> ... -> posix_writev() |
there are 4 iot_worker thread doing the 128KB IO write fops as above, but only one can execute __posix_writev function and the others have to wait.
however, if the afr volume is configured on with storage.linux-aio which is off in default, the iot_worker will use posix_aio_writev instead of posix_writev to write data.
the posix_aio_writev function won't be affected by GLUSTERFS_WRITE_IS_APPEND, and the AFR volume write performance goes up.
So, my question is whether AFR volume could work fine with storage.linux-aio configuration which bypass the GLUSTERFS_WRITE_IS_APPEND setting in afr_writev,
and why glusterfs keeps posix_aio_writev different from posix_writev ?
Any replies to clear my confusion would be grateful, and thanks in advance.
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