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[Bug tapsets/19875] New: membarrier missing from syscall tapset
- From: "dsmith at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sourceware dot org
- Date: Mon, 28 Mar 2016 14:43:56 +0000
- Subject: [Bug tapsets/19875] New: membarrier missing from syscall tapset
- Auto-submitted: auto-generated
https://sourceware.org/bugzilla/show_bug.cgi?id=19875
Bug ID: 19875
Summary: membarrier missing from syscall tapset
Product: systemtap
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: tapsets
Assignee: systemtap at sourceware dot org
Reporter: dsmith at redhat dot com
Target Milestone: ---
The membarrier syscall was added in kernel 4.3 by the following kernel commit:
====
commit 5b25b13ab08f616efd566347d809b4ece54570d1
Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri Sep 11 13:07:39 2015 -0700
sys_membarrier(): system-wide memory barrier (generic, x86)
Here is an implementation of a new system call, sys_membarrier(), which
executes a memory barrier on all threads running on the system. It is
implemented by calling synchronize_sched(). 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
[1], rwlocks), the read-side can be accelerated significantly by moving
the bulk of the memory barrier overhead to the write-side.
====
Support for membarrier() should be added to the syscall tapset.
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