----- Original Message ----- > From: "Josh Triplett" <j...@joshtriplett.org> > To: "Mathieu Desnoyers" <mathieu.desnoy...@efficios.com> > Cc: linux-kernel@vger.kernel.org, "KOSAKI Motohiro" > <kosaki.motoh...@jp.fujitsu.com>, "Steven Rostedt" > <rost...@goodmis.org>, "Paul E. McKenney" <paul...@linux.vnet.ibm.com>, > "Nicholas Miell" <nmi...@comcast.net>, > "Linus Torvalds" <torva...@linux-foundation.org>, "Ingo Molnar" > <mi...@redhat.com>, "Alan Cox" > <gno...@lxorguk.ukuu.org.uk>, "Lai Jiangshan" <la...@cn.fujitsu.com>, > "Stephen Hemminger" > <step...@networkplumber.org>, "Andrew Morton" <a...@linux-foundation.org>, > "Thomas Gleixner" <t...@linutronix.de>, > "Peter Zijlstra" <pet...@infradead.org>, "David Howells" > <dhowe...@redhat.com>, "Nick Piggin" <npig...@kernel.dk> > Sent: Sunday, March 15, 2015 11:25:50 PM > Subject: Re: [RFC PATCH] sys_membarrier(): system/process-wide memory barrier > (x86) (v12) > > On Sun, Mar 15, 2015 at 03:24:19PM -0400, Mathieu Desnoyers wrote: > > Here is an implementation of a new system call, sys_membarrier(), which > > executes a memory barrier on either all running threads of the current > > process (MEMBARRIER_PRIVATE_FLAG) or calls synchronize_sched() to issue > > a memory barrier on all threads running on the system. It can be used to > > distribute the cost of user-space memory barriers asymmetrically by > > transforming pairs of memory barriers into pairs consisting of > > sys_membarrier() and a compiler barrier. For synchronization primitives > > that distinguish between read-side and write-side (e.g. userspace RCU, > > rwlocks), the read-side can be accelerated significantly by moving the > > bulk of the memory barrier overhead to the write-side. > > From a quick review, this seems quite reasonable (as it did 5 years > ago). > > One request: Could you please add a config option (default y) in the > EXPERT menu to disable this? You actually seem to already have it > marked as a cond_syscall.
Sure, done. > > Also, a very minor nit: flags in kernel APIs aren't typically named with > a _FLAG suffix. OK, good point. > > With the syscall made optional, and with or without that naming nit > fixed: > Reviewed-by: Josh Triplett <j...@joshtriplett.org> Thanks! Mathieu > > - Josh Triplett > -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
