> > Don't forget that all IO requests are queued on the device. With a > modern HW and disk you usually have NCQ and most drives will throw > away write request to the same sector if they see a later write to > the same sector in the queue. > > That said. There is nothing wrong with writing again and again to > the same sector on disk. File/record locking is done at the FileSystem > level. An application that wants exclusive write need to open the file > that way. Other wise it could even be written from another machine not > even another thread. > > What is it you are concerned with? > I happen to read the email and have a question, that may not be Erez's real question :) Let's suppose the following example: 1 pdflush find a dirty inode and decides to flush a set of dirty pages to harddrive 2 while this set of dirty pages is being committed to harddrive(dma_mapping is done, but dirty pages are not really written to disk media), application/FS is trying to update some pages in this set of dirty pages. Then what happens? Will application be put into sleep until page flushing to disk media is done? Thanks, Forrest -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
