Kanchan, > For NAND based SSDs, mixing of data with different life-time reduces > efficiency of internal garbage-collection. During FS operations, > series of journal updates will follow/precede series of data/meta > updates, causing intermixing inside SSD. By passing a write-hint with > journal, its write can be isolated from other data/meta writes, > leading to endurance/performance benefit on SSD. Why not just introduce REQ_JOURNAL and let the device driver decide how to turn that into something appropriate for the device? That's what I'll need for SCSI. Existing SCSI streams are not a good fit. -- Martin K. Petersen Oracle Linux Engineering
