[dm-devel] [PATCH V6 0/2] multipath-tools: intermittent IO error accounting to improve reliability

[Guan Junxiong]

Hi，Martin and Muneendra

Any feedback about this version of patches?
If this version looks good for you, can I add your reviewed-by tags into the next version?

Looking forward to you reply.

Regards
Guan Junxiong


On 2017/9/21 21:43, Guan Junxiong wrote:
> Hi ALL,
> 
> This patchset add a new method of path state checking based on accounting
> IO error. This is useful in many scenarios such as intermittent IO error
> an a path due to network congestion, or a shaky link.
> 
> PATCH 1/2 implements the algorithm that sends a couple of continuous IOs
> to a path which suffers two failed events in less than a given time. Those
> IOs are sent at a fix rate of 10 Hz.
> PATCH 2/2 discard the original algorithm because of this:
> the detect sample interval of that path checkers is so big/coarse that
> it doesn't see what happens in the middle of the sample interval. We have
> the PATCH 1/2 as a better method.
> 
> 
> Changes from V5:
> * rebase on the latest release 0.7.3 
> 
> 
> Changes from V4:
> * path_io_err_XXX -> marginal_path_err_XXX. (Mumeendra)
> * add one more parameters named marginal_path_double_failed_time instead
>   of the fixed 60 seconds for the pre-checking of a shaky path. (Martin)
> * fix for "reschedule checking after %d seconds" log 
> * path_io_err_recovery_time -> marginal_path_err_recheck_gap_time.
> * put the marginal path into PATH_SHAKY instead of PATH_DELAYED 
> * Modify the commit comments to sync with the changes above.
> 
> 
> Changes from V3:
> * add a patch for discard the san_path_XXX_feature 
> * fail the path in the kernel before enqueueing the path for checking
>   rather than after knowing the checking result to make it more
>   reliable. (Martin)
> * use posix_memalign instead of manual alignment for direct IO buffer. (Martin) 
> * use PATH_MAX to avoid certain compiler warning when opening file
>   rather than FILE_NAME_SIZE. (Martin)
> * discard unnecessary sanity check when getting block size (Martin)
> * do not return 0 in send_each_aync_io if io_starttime of a path is
>   not set(Martin)
> * Wait 10ms instead of 60 second if every path is down. (Martin)
> * rename handle_async_io_timeout to poll_async_io_timeout and use polling
>   method because io_getevents does not return 0 if there are timeout IO
>   and normal IO.
> * rename hit_io_err_recover_time ro hit_io_err_recheck_time 
> * modify the multipath.conf.5 and commit comments to keep sync with the
>   above changes
> 
> 
> Changes from V2:
> * fix uncondistional rescedule forverver
> * use script/checkpatch.pl in Linux to cleanup informal coding style
> * fix "continous" and "internel" typos
> 
> 
> Changes from V1:
> * send continous IO instead of a single IO in a sample interval (Martin)
> * when recover time expires, we reschedule the checking process (Hannes)
> * Use the error rate threshold as a permillage instead of IO number(Martin)
> * Use a common io_context for libaio for all paths (Martin)
> * Other small fixes (Martin)
> 
> 
> Junxiong Guan (2):
>   multipath-tools: intermittent IO error accounting to improve
>     reliability
>   multipath-tools: discard san_path_err_XXX feature
> 
>  libmultipath/Makefile      |   5 +-
>  libmultipath/config.c      |   3 -
>  libmultipath/config.h      |  21 +-
>  libmultipath/configure.c   |   7 +-
>  libmultipath/dict.c        |  88 +++---
>  libmultipath/io_err_stat.c | 744 +++++++++++++++++++++++++++++++++++++++++++++
>  libmultipath/io_err_stat.h |  15 +
>  libmultipath/propsel.c     |  70 +++--
>  libmultipath/propsel.h     |   7 +-
>  libmultipath/structs.h     |  15 +-
>  libmultipath/uevent.c      |  32 ++
>  libmultipath/uevent.h      |   2 +
>  multipath/multipath.conf.5 |  89 ++++--
>  multipathd/main.c          | 140 ++++-----
>  14 files changed, 1043 insertions(+), 195 deletions(-)
>  create mode 100644 libmultipath/io_err_stat.c
>  create mode 100644 libmultipath/io_err_stat.h
>