linux/include/uapi
Mathieu Desnoyers a961e40917 membarrier: Provide register expedited private command
This introduces a "register private expedited" membarrier command which
allows eventual removal of important memory barrier constraints on the
scheduler fast-paths. It changes how the "private expedited" membarrier
command (new to 4.14) is used from user-space.

This new command allows processes to register their intent to use the
private expedited command.  This affects how the expedited private
command introduced in 4.14-rc is meant to be used, and should be merged
before 4.14 final.

Processes are now required to register before using
MEMBARRIER_CMD_PRIVATE_EXPEDITED, otherwise that command returns EPERM.

This fixes a problem that arose when designing requested extensions to
sys_membarrier() to allow JITs to efficiently flush old code from
instruction caches.  Several potential algorithms are much less painful
if the user register intent to use this functionality early on, for
example, before the process spawns the second thread.  Registering at
this time removes the need to interrupt each and every thread in that
process at the first expedited sys_membarrier() system call.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-10-19 22:13:40 -04:00
..
asm-generic Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2017-09-11 18:34:47 -07:00
drm Merge branch 'drm-vmwgfx-next' of git://people.freedesktop.org/~syeh/repos_linux into drm-next 2017-08-29 10:38:14 +10:00
linux membarrier: Provide register expedited private command 2017-10-19 22:13:40 -04:00
misc uapi: export all headers under uapi directories 2017-05-11 00:21:54 +09:00
mtd uapi: export all headers under uapi directories 2017-05-11 00:21:54 +09:00
rdma IB/core: Fix typo in the name of the tag-matching cap struct 2017-09-25 11:47:23 -04:00
scsi scsi: cxlflash: Support AFU debug 2017-06-26 15:01:12 -04:00
sound Merge remote-tracking branch 'asoc/topic/intel' into asoc-next 2017-09-01 12:12:19 +01:00
video uapi: export all headers under uapi directories 2017-05-11 00:21:54 +09:00
xen uapi: export all headers under uapi directories 2017-05-11 00:21:54 +09:00