On Mon, Apr 20, 2009 at 11:53:12AM -0700, Curt Wohlgemuth wrote: > > > Since the s_mb_history buffers are allocated at mount time only, > > and later writing to mb_hist_size does not affect their size, > > it means that mb_hist_size must be set before the filesystems are > > mounted. However, that makes it impossible to tune the root > > filesystem history size, and at best it is difficult to tune the > > other filesystems because the value has to be set by an init > > script after root mounts but before other filesystems mount. If it's only going to be allocated at mount-time (as opposed doing it at run-time --- where for simplicities sake I would just simply flush the existing history when resizing the mb_history buffers), I would make this a mount option. This would allow it to be set for the root filesystem via a boot option (rootfsflags). > Right, I thought about this. But avoiding the race when the tunable is > being changed at the same time that history is being updated just didn't > seem worth it to me. Fixing this wouldn't be that hard; I would use read-copy-update (RCU) and just free the old history when changing the size of the mb_history. But setting it as a mount option would also be fine, I think. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
