[dm-devel] [PATCH 00/12] multipath-tools: improve processing efficiency for addition and deletion of multipath devices

[tang.junhui at zte.com.cn]

From: tang.junhui <tang.junhui at zte.com.cn>

Hello Christophe, Ben, Hannes, Martin, Bart, and other guys:

The twelve patches in this series are used to improve processing
efficiency for addition and deletion of multipath devices.

These patches are tested pass by ZTE multipath automatic testing syetem.
The modification reduces the system consumption(such as CPU) and shortens
the processing time obviously in scene of massive multipath devices
addition or deletion.

The main processing flow of code is:
1)uevents accumulation in uevents burst scene:
  --[pacth]libmultipath: wait one seconds for more uevents in
    uevent_listen() in uevents burst situations
2)uevents filtering and merging:
  --[pacth]multipathd: merge uevents before proccessing
  --[pacth]libmultipath: filter uevents before proccessing
3)uevents proccessing:
  --[pacth]multipathd: add need_do_map to indicate whether need calling
    domap() in ev_add_path()
  --[pacth]multipathd: add need_do_map to indicate whether need calling
    domap() in ev_remove_path()
  --[pacth]multipathd: proccess merged uevents

There are some patches providing basic struct members or maros which
would used in above pathes:
  --[patch]libmultipath: add wwid for "struct uevent" to record wwid of
    uevent
  --[patch]libmultipath: add merge_node for "struct uevent" to record
    nodes of merged uevents
  --[patch]libmultipath: add two list iteration macros

There are also some independent optimization pathes for further
improvement:
  --[patch]multipathd: move uev_discard() to uevent.c and change its name
    to uevent_can_discard()
  --[patch]multipathd: move calling filter_devnode() from uev_trigger() to
    uevent_can_discard()
  --[patch]libmultipath: use existing wwid when wwid has already been
    existed in uevent

Any comment will be welcome, and it would be appreciated if these
patches would be considered for inclusion in the upstream
multipath-tools.

Thank you all,
Tang Junhui