Thanks for the reply. Jun On Sat, Jun 25, 2016 at 2:34 PM, Jens Axboe <axboe@xxxxxxxxx> wrote: > On 06/25/2016 11:04 AM, Jun He wrote: >> >> Hi all, >> >> I use the output of blktrace as the input of my block device simulator. >> Now I >> want to add semantics of data stored in each block to the output, so >> my simulator can use them. For example, I would like to know if the block >> is >> storing file data or file system metadata. If it is metadata, I'd like to >> know >> what kind of metadata it is. For example, ext4's superblock, inode table, >> blockbitmap, or extent tree block ... If it is file data, I'd like to know >> its filename. >> >> Output of blkparse may look like: >> >> op block# semantics >> w 43 inode-table >> w 88 directory-entries >> r 48 file-data(/home/user1/data) >> w 77 extent-tree-block >> w 777 journal >> >> Statically, I can get the semantics of, for example, ext4 by debugfs and >> dumpe2fs. And this is fine for most of the cases since the format of ext4 >> is >> mostly fixed (blocks that store inode table will always store inode >> table). But >> the data semantics in a block does change over time in some case. For >> example, a >> block can store file data at a time and extent tree block at another time. >> So I >> cannot use the statically collected semantics to feed my simulator. >> >> Is outputting semantics already supported by blktrace? >> >> If not, any suggestions for implementing it? > > > The kernel marks certain IO as being meta data, and blktrace/blkparse > understands this and carries this information to user space. What you are > looking for is a further split of meta data into categories. This would need > to be annotated on the kernel front, and the blktrace format extended to > understand that we have multiple kinds of meta data. Currently we don't have > that. > > > -- > Jens Axboe > -- To unsubscribe from this list: send the line "unsubscribe linux-btrace" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
