On Tue 10-05-11 10:59:15, OGAWA Hirofumi wrote: > "Darrick J. Wong" <djwong@xxxxxxxxxx> writes: > > > To assess the performance impact of stable page writes, I moved to a disk that > > doesn't have DIF support so that I could measure just the impact of waiting for > > writeback. I first ran wac with 64 threads madly scribbling on a 64k file and > > saw about a 12 percent performance decrease. I then reran the wac program with > > 64 threads and a 64MB file and saw about the same performance numbers. As I > > suspected, the patchset only seems to impact workloads that rewrite the same > > memory page frequently. > > > > I am still chasing down what exactly is broken in ext3. data=writeback mode > > passes with no failures. data=ordered, however, does not pass; my current > > suspicion is that jbd is calling submit_bh on data buffers but doesn't call > > page_mkclean to kick the userspace programs off the page before writing it. > > > > Per various comments regarding v3 of this patchset, I've integrated his > > suggestions, reworked the patch descriptions to make it clearer which ones > > touch all the filesystems and which ones are to fix remaining holes in specific > > filesystems, and expanded the scope of filesystems that got fixed. > > > > As always, questions and comments are welcome; and thank you to all the > > previous reviewers of this patchset. I am also soliciting people's opinions on > > whether or not these patches could go upstream for .40. > > I'd like to know those patches are on what state. Waiting in writeback > page makes slower, like you mentioned it (I guess it would more > noticeable if device was slower that like FAT uses). And I think > currently it doesn't help anything others for blk-integrity stuff > (without other technic, it doesn't help FS consistency)? > > So, why is this locking stuff enabled always? I think it would be better > to enable only if blk-integrity stuff was enabled. > > If it was more sophisticate but more complex stuff (e.g. use > copy-on-write technic for it), I would agree always enable though. Well, also software RAID generally needs this feature (so that parity information / mirror can be properly kept in sync). Not that I'd advocate that this feature must be always enabled, it's just that there are also other users besides blk-integrity. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- 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
