| Message ID | 20220128155841.39644-1-snitzer@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | block/dm: fix bio-based DM IO accounting | expand |
On Fri, 28 Jan 2022 10:58:38 -0500, Mike Snitzer wrote: > [this v4 is final iteration, should be "ready"...] > > Hi Jens, > > Just over 3 years ago, with commit a1e1cb72d9649 ("dm: fix redundant > IO accounting for bios that need splitting") I focused too narrowly on > fixing the reported potential for redundant accounting for IO totals. > Which, at least mentally for me, papered over how inaccurate all other > bio-based DM's IO accounting is for bios that get split. > > [...] Applied, thanks! [1/3] block: add bio_start_io_acct_time() to control start_time commit: 5a6cd1d29f2104bd0306a0f839c8b328395b784f [2/3] dm: revert partial fix for redundant bio-based IO accounting commit: b6e31a39c63e0214937c8c586faa10122913e935 [3/3] dm: properly fix redundant bio-based IO accounting commit: 3c4ae3478082388ae9680a932d6bfd54c10fca0d Best regards,
[this v4 is final iteration, should be "ready"...] Hi Jens, Just over 3 years ago, with commit a1e1cb72d9649 ("dm: fix redundant IO accounting for bios that need splitting") I focused too narrowly on fixing the reported potential for redundant accounting for IO totals. Which, at least mentally for me, papered over how inaccurate all other bio-based DM's IO accounting is for bios that get split. This set fixes things up properly by allowing DM to start IO accounting _after_ IO is submitted and a split may have occurred. The proper start_time is still established (prior to submission), it is passed in to a new bio_start_io_acct_time(). This eliminates the need for any DM hack to rewind block core's accounting that was started before any potential bio split. All said: If you'd provide your Acked-by(s) I'm happy to send this set to Linus for v5.17-rc (and shepherd the changes into stable@ kernels). Or you're welcome to pickup this set to send along (I'd obviously still do any stable@ backports). NOTE: the 3rd patch references the linux-dm.git commit id for the 1st patch.. so that'll require tweaking no matter who sends the changes to Linus. Please advise, thanks. Mike v4: added Christoph's Reviewed-bys. Removed READ_ONCE from patch 3 v3: fix patch 3 to call bio_start_io_acct_time v2: made block changes suggested by Christoph Mike Snitzer (3): block: add bio_start_io_acct_time() to control start_time dm: revert partial fix for redundant bio-based IO accounting dm: properly fix redundant bio-based IO accounting block/blk-core.c | 25 +++++++++++++++++++------ drivers/md/dm.c | 20 +++----------------- include/linux/blkdev.h | 1 + 3 files changed, 23 insertions(+), 23 deletions(-)