From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=jzOWgCWtp0qqMh8NbWbP5thzm/P9zY/fFflhz7GLVBY=; b=cOdaOm2qGYWKJFfoqrI60ZOvmuHJGr+rPc2os3MagKeP7y7a2tPtTb4onTcjRxcQyb 5slR4hb882duVEDzsUvP23hJhzwtUuORwnUVYecMGTwYVc+JRECAA6DFEBGxK2+eeTBt gtZ7XTpfBK5BMyePSOP7DZpfdKLHxv3h5XhjVBXs2q3bo/Lv5mDLG0uat+mrx6KuNJaG R7BPhH2474G6Es+zkw7Bmkk1fa20Rm81ddH/kSDkfIZkGkog9cYjTqzVqc2xEc6GQqCf KRTPGL4trY59TN014+Z1D6PsQ/IwUN8Qo+3BkZg5okG2dmMZ+mUsIaNOA9U6Fl9rfNSk 11Bw== From: Junchang Wang Subject: [PATCH] memorder: Add a brief description of the use of multicopy atomicity Date: Thu, 8 Nov 2018 10:21:31 +0800 Message-Id: <1541643691-8116-1-git-send-email-junchangwang@gmail.com> To: paulmck@linux.vnet.ibm.com, akiyks@gmail.com Cc: perfbook@vger.kernel.org, Junchang Wang List-ID: Subsection Multicopy Atomicity is ahead of Subsection Hardware Specifics where implementation detail of multicopy atomicity in mainstream architectures is presented. So we add (1) a brief description of the use of multicopy atomicity in representative architectures and (2) a reference to Table Summary of Memory Ordering, in subsection Multicopy Atomicity. The description is borrowed from a nice discussion with Paul, which can be found at https://www.spinics.net/lists/perfbook/msg01952.html. Signed-off-by: Junchang Wang --- memorder/memorder.tex | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/memorder/memorder.tex b/memorder/memorder.tex index fba49b7..69ce196 100644 --- a/memorder/memorder.tex +++ b/memorder/memorder.tex @@ -1901,7 +1901,11 @@ Most CPU vendors interested in providing multicopy atomicity have therefore instead provided the slightly weaker \emph{other-multicopy atomicity}~\cite[Section B2.3]{ARMv8A:2017}, which excludes the CPU doing a given store from the requirement that all -CPUs agree on the order of all stores. +CPUs agree on the order of all stores.\footnote{ + As of late 2018, ARMv8 and x86 provide other-multicopy atomicity, + IBM mainframe provides fully multicopy atomicity, and PPC does + not provide multicopy atomicity at all. More detail is shown in + Figure~\ref{tab:memorder:Summary of Memory Ordering}.} This means that if only a subset of CPUs are doing stores, the other CPUs will agree on the order of stores, hence the ``other'' in ``other-multicopy atomicity''. -- 2.7.4