Re: [PATCH 00/12] multipath: new and rebased patches

["Benjamin Marzinski" <bmarzins@redhat.com>]

Ooops. I accidentally used your old email for this patchset, Christophe.

-Ben

On Wed, Mar 14, 2018 at 12:46:33PM -0500, Benjamin Marzinski wrote:
> Patches 1-5 are minor bug fixes and a unit test for basenamecpy.
> 
> Patch 6 is revised version of my nanosleep patch, that only changes
> the checkerloop code, since that is the only time when multipathd
> actually sets an alarm without locking.
> 
> Patches 7-11 are a rebase of my "alternate dmevents waiter method"
> patchset.  The only code that has changed outside of rebasing them is in
> patch 11.  It adds a function, remove_map_by_alias(), and uses it in
> dmevent_loop(). This simply moves the code the gets the multipath device
> out of dmevents.c, so it can work exclusively in device names.  It also
> changes the names of the functions the initialize and cleanup the
> dmevents polling code to match similar multipathd functions and adds
> a Makefile define to disable using the polling code, both suggested
> by Martin Wilck.
> 
> Patch 12 is unit testing code for the new code in dmevents.c
> 
> Here is the description from my initial posting of the alternate dmevents
> waiter method" patchset:
> 
> This patchset implements a new method of getting dmevents for
> multipathd.
> 
> With the existing wait code, multipathd needs to create a waiter thread
> for every multipath device. This can become very wasteful in setups with
> large numbers of multipath devices. These duplicate threads all are
> serialized to update the multipath devices, so they don't actually speed
> up dmevent handling.
> 
> The new method uses the new dmevent polling ability introduced in the
> 4.37.0 device-mapper kernel module.  The original method has been
> retained for backwards compatablility, and it is possible to force
> multipathd to use the orignal method on newer kernels. The benefit of
> this new method is that there is only one thread necessary to wait on
> dmevents, which can be started when device-mapper starts, and stopped
> during shutdown, just like the other main threads.
> 
> These patches use device-mapper features that don't have a libdevmapper
> API.  They will switch over as soon as support is available in
> libdevmapper.
> 
> Benjamin Marzinski (12):
>   Unit tests for basenamecpy
>   libmultipath: fix basenamecpy
>   libmultipath: set dm_conf_verbosity
>   multipathd: log thread cleanup
>   libmultipath: fix log_pthread processing
>   multipathd: use nanosleep for strict timing
>   libmultipath: move remove_map waiter code to multipathd
>   move waiter code from libmultipath to multipathd
>   call start_waiter_thread() before setup_multipath()
>   libmultipath: add helper functions
>   multipathd: add new polling dmevents waiter thread
>   multipath: add unit tests for dmevents code
> 
>  Makefile.inc               |   3 +
>  libmultipath/Makefile      |   2 +-
>  libmultipath/devmapper.c   |  29 +-
>  libmultipath/devmapper.h   |   3 +-
>  libmultipath/log_pthread.c |  40 +--
>  libmultipath/log_pthread.h |  10 +-
>  libmultipath/structs_vec.c | 140 +-------
>  libmultipath/structs_vec.h |   8 +-
>  libmultipath/util.c        |  25 +-
>  libmultipath/util.h        |   2 +-
>  libmultipath/vector.c      |  16 +-
>  libmultipath/vector.h      |   1 +
>  libmultipath/waiter.c      | 215 ------------
>  libmultipath/waiter.h      |  17 -
>  multipathd/Makefile        |   6 +-
>  multipathd/dmevents.c      | 392 +++++++++++++++++++++
>  multipathd/dmevents.h      |  13 +
>  multipathd/main.c          | 230 ++++++++++--
>  multipathd/waiter.c        | 215 ++++++++++++
>  multipathd/waiter.h        |  17 +
>  tests/Makefile             |   9 +-
>  tests/dmevents.c           | 847 +++++++++++++++++++++++++++++++++++++++++++++
>  tests/util.c               | 167 +++++++++
>  23 files changed, 1944 insertions(+), 463 deletions(-)
>  delete mode 100644 libmultipath/waiter.c
>  delete mode 100644 libmultipath/waiter.h
>  create mode 100644 multipathd/dmevents.c
>  create mode 100644 multipathd/dmevents.h
>  create mode 100644 multipathd/waiter.c
>  create mode 100644 multipathd/waiter.h
>  create mode 100644 tests/dmevents.c
>  create mode 100644 tests/util.c
> 
> -- 
> 2.7.4
> 
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